REPORT s.. ii.;s Mil DIIIKUINMIUMll IK\(I IIIMKMSIN S \ l l K \ l I)I\M(I\I)M:\ l\M Kl Ml \l \l \H IKUS \ ( l l \ \ll<)\ \N\nsis I J I' I S.IU.I,,,;! i J I' I SclUihup i I I \\ Mcilf DM. ISil>ln <..Y hr.isnuis II W lesii K.J.I). K.ibk M M.iv. I"7S 4KH<>'' 2
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REPORT s . . i i . ; s
Mil D I I I K U I N M I U M l l I K \ ( I I I I M K M S I N S \ l l K \ l I ) I \ M ( I \ I ) M : \ l \ M Kl Ml \ l \ l
\ H I K U S \ ( l l \ \ l l < ) \ \ N \ n s i s
I J I' I S.IU.I,,,;!
i J I' I SclUihup i I I \\ Mci l f
DM. ISil>ln <..Y hr.isnuis II W lesi i K.J.I). K.ibk
M M.iv. I"7S
4KH<>''
2
4» NATIONAL INSTITUTE FOR METALLURGY
NASIONALE INSTITUUT VIR METALLURGIE
R f P O R l • VFRSLACi V... lf>?K
l l l l - P M H i M I N V l l O N O l TK \ ( > H . K M K M S IN NA 11 KAl OIAMONDS BY I N M K l M I - N I A I N f l TKOVAC I I V A HON ANALYSE
1 st \ U \ I T 5
Itmstifiaturs O W Uihliv <' S I risrmis IIW I t s i I j I) k^t.lc
ISBN 0 86999 176 0
S Y N O P S I S
\ in'*! nt more than 15'M) imliuikal litamiimls. ilisuleil into '"> samples, nas anals se>i Ihcsc were obtained from three South African mines Premier, hinwS. anil lagcrstontctn
I * .• presence ot 44 elemental in ihamomls was cstahhshcii from M isot.iprs .in*! lUMiriumc rcMilis. were otnaineil 1<>r }4 elements.
s \ \i r v A i r i \ Í;
Daar is altcsame 15<M* atsomierhke iliamantr ontiecil ivat in •>»> monsters icr.iee! «as llirr.lic iliamante was afkotmlii! ian itne Suiil Unkaansc mvnr Premier, I -insert cn Ja^rrstuntcin
Die aanwcsi^hcul v.iii 44 clemcrte is in tie diamante vas^cstcl van M isotope en ilaar is k w a n t i u t i e w resu.tate sir J4 elcmente verkr\
« n v i \ \ r s
1 IS I KOI) ! ( I ! ! > \
.' I \ l " l K IMI N I \ l Ml I HOI) 2 1 M i l l I I O \ Ol 1)1 \ \ K ) \ I ) S 2 2 ( I I \ M \ ( , Ol 1)1 M H i M i s ? > IKK \ l > ! \ I ION < O N D I I I O N s W D I I I \ « O S I I I I K I M , 2 I < Ol \ I I N ( , I Ol I I 'MI \ !
2 4 1 \ l H S\»n-::: 2 * -' \ I' K I \\sr< -1-.
2 < 'J l \ l I I \ l l \ I VW>KK 2 (. IJI W I I I M I U 1)1 I I K M I W I U>\ Ol M I O K I I l \ I I) ISOIOIM s 2 " <Jl \ M I I \ I I U 1)1 I I KMIN \ I I O N Ol I ON( , I l \ I I) ISOIOIM s 2 ,H i i M I i s o i I » i i i HON 2 •' D M A Kl I ) ! I H O N
5 KI SI I I s ; i I ( I IKOMH M „ .! 2 M \ \ ( . A M s | I 3 ( Ol ' l ' l K „ í 4 AN I IUON- i " „ ' ? l i \ K I I M „ < ' , ( I KM M „ »7 V I I I K H I I M „ i X I I I I I K I l ' M
4 DISC I SSION A M ) « O N U I SION
5 \< KNOWI I I K . I M I N I S
f> K l I I K l \ ( I S
fable I Neutron H U M S .«nil cadmium ratios y table 2 Isotopes positively identif ied in n.itur.il diamonds ') fable ! Kock standards used I I Table 4 Kadionmlulcs ot sagnititanct- tor i|iiantnafivc work 12 Table 5 trace elements in Premier diamonds | J Tiit-lr (i trace elements in I insch diamonds |4 tabic 7 I r a n elements in larcrslontcin diamonds 15 fable Js I race elements in diamonds trom unknown sources | n
fable V Decav times alter which the isotopes Wire detected, standards, and detection | ; l imits
LIST OK ILLUSTRATIONS
l'i|>urt' I Dcc.iv m m tor scandium 4f> IS 11)!iire 2 Dccav curve lor lanthanum 14(1 and iridium-1'»2 19 l i f iurc J Dccav curve tor l iarium 151 20 f igure 4 Decav curve for vanadium 52 21
A C f l N O I X A SUMMARV Ol I ' l l I I 'KI VIOUS WORK ON N A T U R A L DIAMONDS 22
Table I I A nummary o f some elements and compounds detected and measured in diamonds 23
1. INTRODUCTION Natural diamonds arr protiabl» formed in the harths upper mantle from igneous mclis' '"' tmt.
owing to the diamond % inert and impermeable nature, accidental inclusions of surrounding magma or co-precipttating minerals arc not chemically affected bv the diamond's ascent to the f arth's surface.
The amounts ot impurities present in diamonds can »ar\ vonside'alii» 1 p to several per ceil o: minerals have been found in boart stones ' and nitrogen !r»r!s r.ighrr than "siMipp ;:i h u e bs-en sletertnincil Nitrogen is responsible tor man» of the spectra! properties nt .ti.i-Tion,! and is in tact used to classify diamonds into different tvpes 'la. lb. and III Koron is thought to I,.- response e fir the Semi-conducting property ot type lib diamonds '
Diamonds that are regarded as inclusion free have a total impurity content ot A few parts per million, anil the purest stones analysed in this investigation had in impurity content ••' >ess than I p.p.m.
the development and improvement ot analytical techniques have led to the determination of more elements at lower levels. I he earliest analyses of diamond were done In wet-! hemic»! methods on the ash left alter the combustion of the diamond in oxygen 1'" With the advent of optical spectrograph», a tar more sensitive too! became available for diamond analvsis. requiring smaller samples and less preparation" '. The volatile impurities found in diamond, which a n he liberated if the diamond is burnt 1 0 or crushed' ', have been studied bv mass spectrometry Infrared spectrometry ha» also been used in the determination ot l l : ( ) and <:0, in the outer mat ot a diamond1*. I lie electron rrmroprobe has l>cen applied to the analysis of colloid-si/ed inclusions v v , ' and ;<> larger crystalline inclusions after thev ha»c l>ecn removed from their diamond matrix' ' ' I he strain patterns associated with the distribution of impurities have been studied by X-ra» topography ''', and the crystal structures of inclusions bv v rav diffraction The results of previous work are summarized in the Appendix.
The most powerful technique used to date for the determination of impurities m diamond is neutron-activation analysis'*"" In a preliminary study l-esq rr .< : 1 , proved instrument.;! neutron-activation analysis to be an extremely sensitive techiiiquc for the analysis of diamond. particular!» because little or no matrix activation occurs and the real Itmits of detection anproach the theoretically possible limits.
A ma|or advantage of instrumental neutron-activation analysis compared with other techr* ,ucs is that it is non-destructive, in that, although the sample suffers considerable radiation damage, it is available for re analysis This nondestructive aspect is understandably of considerable importance with rare or expensive samples such as diamonds
In this work, instrumental ncutron-acttvation analysis was applied to a large suite of carefully selected diamonds. The initial aims of the project were to studv the pcochemistrv of diamonds, to investigate anv possible correlation between the colour of diamonds and their chemistry, and to study the chemistry of the inclusions. The suites of diamonds analysed were selected with these aims in mind and are believed to be the largest, best selected (for the above purposes), and best described suites from specific sources that have been analysed to date.
2. KXPKKIMKNTAI. METHOD 2.1. SM.HCTIO\ Ol MAWtSDS
The diamonds analysed in this work were taken from one month's production of three South African kiml-erlitc mines: Premier in the Transvaal, Tinsch in the Cape ITovince, ami Jagersfontetn in ihc Orange l-ree State. A total of over 1500 stones were grouped into 96 samples, each sample weighing about I gram and consisting of 10 to 25 stones in the sue range 0,25 u- 0.5 carats. All the diamonds in one sample wcie se'ectcd so that they were as nearly identical as possible in colour and quality, and, in the better grades, in size. The samples were divided into eight earegorie* according to colour and the presence or absence of visible inclusions, shades of colour forming sub-categories.
The four main colour categories generally recognized are colourless, yellow, brown, and green, the first three colours being common to most mines. No green stones were available from Jagersfontein, where they are found very rarely. Most of the green stones found in I'insch owe their colour to a thin outer green skin, which is generally accepted as being due to radiation damage 2' from naturally occurring radioactive isotopes.
In practice, the colours found in diamonds do not form clearly separate colour groups, and diamond» vary in colour from colourless through yellow to brown. Similarly, variations of colour from yellow through yellow-green to brown have been found. Diamonds from different mines vary in shade.
1
IRAt l I I I M f M S l \ m.VMOM»
and experience»I diamond sorter* can identify large parn-K oi diamonds from ditícrent sources l>v means of thc.r colour land morphological i characteristics
'Inclusion-tree' stones were defined in this work as stones in which no inclusion*, or strain fields associated with them, could be observed al ><• times magnification with polarucd light. 'Inclusion-containing' stones were selected as those having inclusions that wcr. re.'.lily visible to the naked esc So attempt was made to distinguish between graphitic and non-graphitic inclusions, or between clean inclusions and graphite coated or sulphide-coated tnclusioi s
At the same time as the inclusion free anvl inclusion containing stones were selected, all stones were examined for surface «.racks Stones with cracks were reacted since there was a possibility that the kimberlite mains would enter the bods ot the stone and would IK- extremely difficult to remove.
Hoart samples were also selected, and were grouped with the brown -.amplcs. However, it was realized that boart consists ot a miss !<f fused crystallites ot diamond, which can be expected to include relativeiv large amounts of magma, and which mav a'so be somewhat porous.
The predominant morphology of the better quality stones was dodcvahedral. with some octahedral stones In the poorer-quality samples teg txurt). there were more cleavages iv.A misshapenness,
\ o attempt was made to type these stones according to optical and conduction characteristics into the four accepted categories. However, because natural diamonds arc predominantly type la . the stones used ir, this work ire probably of that type One exception may be sample P", which, irom its orange colour, possibly contains some type lb stones
2.2. ( 7 M V / V . . Ol DIAMOSDS The purity of high-qualitv diamonds KÍU be exceptional, less than 1 p.p.m. of impurities other
than oxygen and possibly nitrogen be.ng tound m some of the diamond samples analysed. I he meticulous cleaning of the diamond surface is therefore essential if meaningful results are to be obtained, the cleaning is made difficult by the presence of trigons and other growth and dissolution features, or micro-cracks 10 to 20 ^m deep, which are possibly due to percussion damage3 .
However, owing to the good chemical resistance of diamonds, rigorous cleaning techniques involving strong acids and oxidizing agents can be used The following procedure was used before, and in most cases also after, neutron irradiation (1) hot hydrofluoric and sulphuric acids ( 1 to 1 ) for 2 hours (to remove adhering silicate matter). (2) hot mine acid for 3() minutes, repeated twice, (3) hot distilled water for 5 minutes, repeated twite, (4) two washes in acetone, (5) air-drying. All the reagents employed were of analytical grade and were used without further purification. Procedures involving hydrofluoric acid were carried out in new Teflon-ware previously cleancM with the acid mixture used. The other cleaning procedures were carried out in horosilicate glassware that had been cleaned in hot nitri: acid before use.
After being rlntvd, the samples were weighed and scaled in high-purity polyethylene vials for the short irradiation. The cleaning and weighing were done in a laboratory specially constructed for this purpose, whuh had a filtercd-air supply and contained only fiosc chemicals required for the cleaning.
The cleaning appeared to be satisfactory for the high quality diamonds, since the results after rccleaning and re-analysis were identical to the earlier results. In the boart samples there was some evidence, after the repeated cleaning and analysis, that the impurities had been leached.
2.J. IRRA»)AIIOS COSMTIOSS AM) H.VX MOSITORISV All the irradiations were carried out in the Oak Ridge Research Reactor, Safari I, at the South
African Atomic I nergy Hoard, Pclindaba, short irradiations of up to 30 minutes being done in the pneumatic facility. High-purity polyethylene 'rabbits' could be used in this facility, the diamonds being sealed in smaller polyethylene vials inside them. The long irradiations were carried out in the poolside facility, the diamonds being scaled in quartz vials. Six of these quart/ vials were sealed in a single high-purity aluminium rabbit. The neutron flux*" and cadmium ratios in these two positions were as shown in Table 1.
The total neutron flux received by each sample was measured by use of a neutron-flux monitor. For the pneumatic irradiations, a 0,5 per cent gold platinum alloy was used for this purpose, the 411 keV peak of the gold-198 isotope (half-life 2,7 days) being used for flux correction. Mux monitoring wa» necessary, although the reactor power (and therefore the total neutron output of the reactor) was held constant to better than 1 per cent, since continual changes were made to the
2
IKAC!' H ! MrVINIS l ) | \MHM)s
loiitigurari -1 <..' the reactor core I hi se resulted in changes i,- .'u utiui nriirron i'uxo i! rhe t.'Xed irradiati» i positions I hr flux monitor used for the poolstdc ir'adiatmns, « is iror toil'", wnich was rolled into ,i sleeve complete!* surrounding the uuart,- tube , ."it a'.-'-g rhr si-.pU !'':- enable.! corrections to be rria.ie !.>r the overall variations in neutron this ir ' tor the fiux era-'i-.-nt across each rabbit 1 his gradient vas found to exceed 5 per cent tor the thermal neutron flux, a;.: i" percent for the fast neutron '' , i \ ' (he iron «oil had the additional i-lvant.u* that txith tr.r . nc—na! neutron arut the fast neutron fluxes .nil.I be monitored simultaneously \ia the reactions
' I e • -) i "* I >• i r"<T-M.. i
and , 4 | t i., f.i " \ | i ! Ifast-
In addition from tlv measured -.itm ot thermal t.. '.ic: nen'ronx. 3 •,ur!\ _'oo.t estimate of the epithcrmal tiux . ould be made'", «hicn reduced lux > orrei <.•<•< c r . i - UK 'hose elements having High epifhermal neutron troys actions
14 cm \11\1. KJIII'XUM luo * orripirfel* separarr . ountinir sv stems were us--<! :n this Mori, one ar rl-e \f,>rn;«. I ner̂ y
Hoard ! \ l (H I'eltndaba. used tor the detection ot short lived isotopes, and the other in the counting laboratories ,n the \iulear I'hvsus Kesrarcb I'nit M ' H l' •• |ohat,-iesburg. «here the long lived isotopes were dttcrmincd
2 4.1. AHi SyUem TN- sv >trm used t«.r the short lived work * onsisted of a III t -n f.e'l.i» lerector. havinj.' .a
resolution ot „>.s ke\ t..r the 1 ' t2 ki \' peak ot coba't ••»> and M efficiency of ~.l ---r cent relative to that of a T5by?5 mm Nal detector This was connected thri 'igh a Canberra 14D8C preamplifier *nA an Hscwt C W - V 4 amphtier to a Packard'»70 series 4tH>0-crianncl analyser Dati ;j;put was to a Kenncdrv tnagiietic tape unit, and the data were processed on an IKM37H14S computer using a modified version of .1 programme by Yule" I be !•'•> Mil' an.ilog-jv to-digital converter of the Hacka'd analyser had the capability ot being operated in the zero dead-time mode described hv Haims I his eliminated any corrections due to varying dead times during the counting period an important source of error when counting times are of the same order as the half lite The problems of pulse pile-up still remained and were reduced to some extent bv the use of a pulser and the application of a pulser-prak correction factor
The detector was shielded bv S cm of lead in the form of an open-ended cylinder 30 cm in length and 15 cm in internal diameter. A sample rotator was constructed that could approach the detector through the open end of the cylinder The rotator was found to be essentia! for tl'is work since the activities of the purest samples were sv, low that they had to he counted I cm from afw' face of the defector; vet they were so iinhotnogcncous tha' countrates could vary In 5" per cent ut that distance2''. Rotation was found to rc.luie the counting errors to a level at which they Were insignificant compared with the errors in the determination ot peak area. The rotator was constructed mainly from I'erspex. /nd was mo.mted on an optical bench ha.ing click-stops at set distances for rapid change', in detector sample distance.
2.4.2. \.P.H.I'. Syti'm
The counting system at the S I* K.l'. laboratories was similar, consisting of a 45 cm 3 Ce(|.i> detector having a resolution of 2,4 per cent for the 13 32 keV peak of cobalr-60, and an efficiency of 9.4 per cent relative to a 75-by-75 mm Nal(TI) detector This was connected through a Canberra 1408C preamplifier and a Canberra 1417 amplifier, which incorporated a baseline restorer, to an Interterhnique Didar 4000 channel analyser with a 100 MM/ analoguc-to-digital converter. Data output was onto an Ampcx magnetic-tape unit. The system ilead time was corrected by use of a pulser leak for the measurement of the total dead time 2*. This reference peak was generated bv a Canberra 1501 stabilization pulser, which was also used in conjunction with Intertechmque digital stabilization circuits in the correction for gair, shifts. Pulse pile-up was avoided bv a system dead time of less than 15 ^er cent, so that pile-up was negligible.
This system waj shielded by a 5 cm cave of old lead, built to contain the countn.g head of an automatic sample changer 3*'' 1 0 at distances of up to .3 cm from the detector face. The counting head incorporated sample rotation for the reasons described above. This rotator was mounted on an optical bench, and, to ensure reproducible positions, a system of verniers and measuring blocks was used to set detector sample distances to better than 0,005 cm.
3
TRACK ELFMFMS IN DIAMONDS
2.5. QIAI.IIAIIM »ORK Preliminary work was undertaken to determine how many elements could be iletermined by
instrumental neutron actuation analvs» in natural diamonds' and by means of what isotopes Two samples were used tor thiN work. One was a collective sample weighing 1.5 g and consisting ot approximately 200 small chips '.Aen from the Premier and rmsch Diamond Mines. IV Beers Pool (Kimberlcyl. and the Consolidated Diamond Mines tie., the tour major diamond-producing regions of South Africa). The chips were ot different colours, and were both inclusion-containing and inclusion free. This was considered to be a good representative diamond sample. The second sample, ten gem-q-alitv diamonds ot different colours, was taken trom Consolidated Diamond Mines
The short-lived isotopes produced from these «amplcs were investigated hv irradiation for 10 minutes and counting for 5 minutes at decay times from 1 to 60 minutes. The long-lived isotopes were investigated in a similar manner. After an irradiation period of 1?0 hours, the samples were repeatedly counted with decav times frim 7 hours to 80 days the counting times varying from 30 minutes to 2 hours-.
The spectra collected were processed, and the peak energies, peak areas, error in peak-area calculation, and decay times were stored on magnetic tape These data were then processed b\ a prognmmc that applied a least-squares fit to a log-linear plot of peak area versus time for each of the gamm. ray peaks found 3''. The half-life was calculated from the best-fu line, which, together with the gamma-ray energy, could be used to obtain an unambiguous identification of the isotope producing that gamma ray. f-rom the same plot, interferences from isotopes having different half lives couid be found. The best decay time (before counting) could be obtained for rjrh, isotope from the minimum shown in a plot of the error in peak-area calculation versus Prr.... I ypical half-life plots are shown in Figures 1 to 4.
From this and later work. 61 isotopes produced by 44 elements were found (Table 2). The gamma-ray peaks used for quantitative analysis were also determined from these results, together with the potentially interfering gamma-rav peaks.
2.6. QUANTITATIVE DETERMINATION OV SHORTLIVED ISOTOPES The work involving the determination of short-lived isotopes was carried out at the reactor in a
small counting laboratory dedicated to this work. The irradiation and counting procedure was as follows. After the diamond samples had been '«radiated for 30 minutes in the pneumatic facility, they were transferred from their container to a clean, unirradiated vial and counted. Two count-, were made: one after a decay time of 90 seconds for 20«) seconds, and the other after 420 seconds for 2000 seconds. The purpose of the first count was to measure the isotopes with half-lives between 60 and 600 seconds with the minimum interference from the longer-lived isotopes, and the second count was to measure these longer-lived isotopes, which had half-lives longer than 600 seconds, after most of the activity from the short-lived isotopes had decayed. The second count could be made closer to the detector owing to the fall in sample activity. This increased the sensitivity of detection for the less active, longer-lived isotopes
The counting system was standardized by the use of analytical-rcagcnt-gradc compounds, either as weighed *• 'ounts of the solid, w 'icrc low specific activities were produced, or as dilute solutions. The solutions we.' made up with a lower limit of 1 fig/ml to avo'd problems of ion adsorption onto the walls of containers, and were micro-pipetted into clean, high-puriy polyethylene vials. The irradiated standards were counted in duplicate at various positions on the optical bench, and distance calibrations were made to calibrate the other pre-set counting positions.
2.1. QUANTITATIVE DETERMINATION OF I.ONGI.IVED ISOTOPES Because these isotopes had longer half-lives, there was time for these samples to i.<r transferred
from the reactor to the counting facilities housed away from the reactor at the N.P.R.U. As previously discussed, the samples were sealed in quartz tubing. These samples were irradiated in batches of 24 for approximately 100 hours in a Predominantly thermal flux of 8 X 10 1 3 n cm" 1 s~' and returned after a 2-day cooling period. The exteriors of the quartz vials were cleaned with hydrochloric acid, water, and acetone for the removal of external contamination. After the tubes had been broken in the Clean Room and the diamonds removed, the diamonds were repeatedly washed in hot nitric acid until no gamma-ray activity was detected in the washings. They were then dried, weighed, and packed into polyethylene vials before being loaded into the magazine of the automatic sample changer. The counting schedule ensured that the maximum amount of data was collected under the best possible conditions. The optimum decay time before counting for each isotope was determined from the qualitative work. From this work, decay timet of 3, 7, 14, 21, 50, and 150 days were selected. The
4
TRACE ELEMENTS IN DIAMONDS
first tount. after ' daw' decav. was for 30 minutes, and the rest of the counts were tor I hour All the samples were counted in duplicate at each decay time, with frequent instrumental checks to avoid unnecessary data loss due to malfunctioning of the equipment.
Standardization was achieved bv the use of the international rock standards prepared bv the United States Ceoiogical Survey ll'SGS) These rock standards were irradiated under the same conditions as the samples, and. after such a long irradiation, they were extremely active and had to be counted at long distances from the detector The accurate dist.-icc calibration previously obtained"* was applied to the data for the standards so thjt the counting positions used for the diamonds could be calibrated. Some elements tor which no data were available from the rock standards, eg. iridium, were standardized bv pipetting of dilute solutions of known concentrations onto graphite, drying, and irradiating under the above conditions. The USdS standards used, the elements standardized, and the values chosen are given in Tables 3 and 4
2.R. IIMITS O'' DETECTION For the following reasons, the limits of detection found in this work approach the theoretical
limits calculated for instrumental neutron-activanon analysis (a) lack of matrix interference from carbon. (b) the high purity of the bettrr-qualirv diamonds, (c) the long irradiation time used, Id) the high fluxes aiailablc. <e) thr low matrix interference from the major elements of the silicate inclusions
All of the above made it possible to determine the trace elements present in the inclusions, which were themselves present at trace levels. For the most-sensitive elements, e.g. vanadium scandium, arsenic, lanthanum, samarium, europium, dysprosium, holmium, lutctium, indium, gold, and thorium, concentrations of about 1 part in HJ1 2 were detectable. At the other extreme, the limits of detection for some of the least sensitive elements determined by instrumental neutron-activation analysis ranged from the 20 ng level for nickel and calcium to the 10 /ig level for sulphui. It should be emphasized that manv of these elements arc not normally regarded as candidates for activation analysis unless they arc present at relatively high concentrations.
2.9. DATA REDUCTION The gamma ray spectra produced in this work were stored on magnetic tape and were processed
on the IBM 360/50 or IBM 370/145 computer at the University of the Witwatersrand. The main computer programme used was a modified version" of 'HEVESEY'. written by Yule 2". This calcalated peak energies and areas, and gave possible isotope identifications. Corrections were made for variations in neutron flux, and for isotope decay. As well as being supplied on hard copy, these data were stored on magnetic tape and were used as the input, together with concentration factors, to a further programme that calculated the concentrations of the various elements.
Obviously, this simple scheme of analysis could be used only where interference-free peaks were found. Initially, interferences were corrected manually until a computer programme was available to apply suitable corrections.
The large amount of data produced (some 2000 gamma-ray spectra) will necessitate sophisticated treatment if maximum information is to be extracted trom them, and modifications and improvements are being made to the data-reduction facilities to enable more detailed results to be obtained.
J. RESULTS The quantitative data obtained in this work are given in Tables 5 to 8. The wide range of levels
found for different elements results in large variations in precision and accuracy; errors arise from the counting statistics for the peak area and from the size of the Complon background beneath the peaks. In general, errors of 40 per ctnt were the maximum found, primarily at the lowest concentrations of the elements. At higher levels of activity, this error decreases rapidly, and errors of 5 to 15 per cent are typical for most results. Where necessary, detection limits were calculated from three standard deviations of the background count in the peak channels.
The data are given to a maximum of three significant figures, which reflects the best estimated precision of this work, viz, about 5 per cent.
Comparison of the data in Table 6 with previously published results1 * shows a generally good agreement except at the lower concentrations of the element*. This discrepancy may be due to improvements in the equipment ot the experimental procedure, which resulted in enhanced sensitive -and precision at lower concentrations. There is also some evidence for the leaching of impurities from
5
TRACE ELEMENTS IN DIAMONDS
some of the inclusion-containing and boart diamonds. Kinally. many of the diamonds clove during the long irradiation, and it is to he expected that inclusions would he exposed on the fresh surfaces I hesc inclusions would be removed or leached bv the hot acids used for cleaning the diamonds, thus resulting in lower concentrations for the elements on the second analysis
The decay times at which the different isotopes were counted, together with the detection limits found and the standards used, arc given in Table 9.
The following elements could be determined from the analysis lines given in Fable 4 without significant interference sodium, magnesium, aluminium, sulphur, chlorine, potassium, calcium, scandium, titanium, vanadium, iron, cobalt, nickel, arsenic, rubidium, stroi.tium. antimony, caesium. barium, lanthanum, samarium, europium, dysprosium, holmium. lutetium. tantalum, indium, and gold. Oxygen was determined by fast neutron-activation analysis !
The dementi for which a significant interference was found on one isotope were chromium, manganese, copper, antimony, barium, cerium, ytterbium, and thorium. The interferences and the precautions taken in obtaining these concentrations arc given below.
3.1. CHROUIIH The 3I(> keV peak of chromium-51 overlapped the 317 keV peak of iridium-1°2. The combined
peak area was correct d bv determination of the iridium 1°2 contribution from the ratio of the 317 keV peak to the interference-free 468 keV peak.
3.2. MAXtiASf.St. The interference-free 1811 keV peak of mangancsc-56 could be used when relatively high levels
of manganese were found. At lower levels, the more sensitive 845 keV peak was used. This interfered with the 844 keV peak of magnesium-27, which could be corrected by the ratio from the 1014 keV peak of magnesium-27.
3.3. COPPER The 1039 keV peak of copper-66 was interfered with by the KHO keV peak of gallium-70. No
correction could be applied for this interference since the other main peak of gallium-70 at 173 keV also had an interference this time from the 172 keV peak of tantilum-182m. Data for copper were therefore calculated on the first count when the 1340 keV peak of coppct-64 was also found, or when the interference from gallium was assumed to be minor because of the absence of other peak? r.g., :' 2201 keV and 2507 keV.
3.4. ASTIMOSY Although data for antimony were calculated from the interference-free 1691 keV peak of
antimony-124, the shorter-lived isotope antimony-122 was also used as a check. However, the 564 keV peak of antimony-122 had an interference from the 564 keV peak of caesium-1 34, and, in samples having high levels of caesium, only the antimony-124 isotope was used.
3.5. BARIl'M The levels for barium were determined from the banum-131 and barium-139 isotopes. The
166 keV peak of barium-139 had a small interference from the 170keV peak of magnesium-27. The ratio of the 170keV peak to the 1014 keV peak of magnesium-27 was used to correct for the contribution to the barium peak.
3.6. CERIUM Two interferences were found on the 145 keV peak of ccnum-141 first, a direct interference
from the 143 keV peak of iron-59, which could be corrected for by subtraction of the iron contribution calculated from the ratio of the 143 keV peak to the interference-free 1099 keV peak of iron-59; second, the 145 keV peak fell on the Compton edge of peaks in the 300 to 320 keV region (predominantly chrcmium-51). which had the effect of broadening the peak boundaries, as determined by the computer programme, and thus increasing the ccnum-141 peak area by large and variable amounts. Corrections for this second error were applied manually to the raw data.
3.1 YTTERBIUM The 198 keV gamma-ray peak of ytterbium-169 had an interference from the 197 keV peak of
terbium-160. A correction was applied based on the ratio of the 197 keV peak to the 887 keV peak of terbium-160. Alternatively, the area of the 197 keV peak was determined after the ytterbium-169 isotope had completely decayed, and was corrected for decay and subtracted from the data obtained after a shore decay. The 396 keV peak of ytterbium-175 had an interference from the 398 keV peak of protactinium-233. A correction was applied bated on the ratio of the 198 keV peak to the 312 keV peak of protactinium-233; or the area of the 398 keV peak of protactinium-233 was determined after a long decay, aid was then corrected and subtracted from the short-decay data.
6
TRACT ELEMENTS IN DIAMONDS
!
i.H IHOKIl 11 Ific 312 keV peak ot protactimum-2 33 'used tor the thorium dctcrn mationi h.i.! an interference
from the 3<»8kcV peak of ir.di'im 1 0 2 \ currco. >n was determined from the ratio of the- 308 keV peak to the interference tree *68 keV peak of indium-192
4 DISCUSSION AND CONCLUSION ihr data presented here have been statistically and gcochcmically "* ' * interpreted I he high
impurm !evcls found ir. the green and brown samples were found to be significantly correlated with thr colours It is therefore possible that the presence of suhmicroscopu mineral inclusions ma\ !>c resr onsible for the colours Alternative or additional reasons for the correlations ma- be that the coloured stones grew under conditions favouring the incorporation of minute inclusions, or that the darker colours prevented some small inclusions from being observed when the stones were categorized.
A significant difference was found in the trace-clement levels of the purer diamonds from Premier, compared with those from l-insch and Jagcrsfontcin I his mas indicate a difference in the growth environment ot diamonds from different sources'*'"
When results of this woi1* arc compared with previous results i Appendix I. there is general agreement tor the higher levels of the elements determined Differences occur ar the lower ievcls, some
' these values being 10 or 1(H» times lower than previous reported values The present report and a paper' * on the same work represent the first published quantitative
determinations, bv ncutron-activatin analysis^ of oxygen, sulphur, chlorine, vanadium, arsenic, rubidium, strontium, terbium, hoimium and tantalum, and the first published qualitative determinations bv the same technique, of germanium, bromine, ncodymium, eadolinium, erbium, and platinum, in diamond.
I he results show that some of these samples are the purest diamonds analysed to date, which reflects favourably on the careful selection procedure used The discovery and determination of many-new elements show the extreme sensitivity of the instrumental neutron-activation technique used here in conjunction with the ideal matrix of carbon
5. ACKNOWLEDGEMENT; fins study was matte (ussiblc through the financial support and co-operation of a number of
organizations and individuals. Thanks arc due to the Anglo American Corporation of South Africa and l>c Beers Industrial Diamonds of South Africa Limited for sponsorship and for the supply of the diamonds used in this study, the University of the Witwatersrand and the South African. Atomic Energy Board for their assistance; Mr J.B. Hawthorne ot the Anglo American Corporation and Drs K.A. Kaal and R.J. Cavcnev of the Diamond Research Laboratory for their encouragement and interest, and Professor DM. Hawkins for his advice and assistance in the statistical treatment of the data.
6. REFERENCES 1. MARX, PC. Hi», sLig . I.onj.. vol 38. 1972. p. 636. 2. KENNEDY, C-.C, and NOROI.IE. BE. I ,,m firnl. vol. 63. 1968, p. 495-3. '"MGNER, P.A. The diamond fields of Southern Africa. Cape Town, C. Struik Ltd. 1971. 4. WILLIAMS, A.F. The genesis of the diamond. London. E. Benn Ltd, 1932. 5. KOCCO. (i.C... CARSON, O.L., and CALL J P hit J. Jppl, HiUÍiat Isotope, vol. 17. 1966.
p. 433. 6. COLLINS, A.T., and WILLIAMS, A.W.S. / Phyy < . vol. 4. 1971. p. 1789. 7. CHRENKO, R.M. Phyy H,v li, vol. 7. 1973. p. 4 ,60 8. CHESLF.Y, E.G. Am. .awtrjlogist, vol. 27. 1942. p. 20. 9. RAAL, E.A. Am. Mwrralogist. vol. 42. 1957. p. 354.
10. EVANS, T. Diamond research 1973. London, Industrial Diamond Distributors, 1973. p. 2. 11. MELTON, C.E., SALOTTI, C.A., and GIARDINI. A.A. Am. MinmhfiM, vol. 57. 1972. p. 1518. 12. CHRENKO, R.M., McDONALD, R.S., and DARROW. K.A. Saturr. l.onJ., vol.213. 1967.
p. 474. 13. SEAL, M.Nature, l.ond., vol. 212. 1966. p. 1528. 14. MEYER, H.O.A., and BOYD, E.R. Ceochm. Cosmochim. Acta, vol. 36. 1972. p. 1255. 15. MEYER, H.O.A., and SVISER0, D.P. International Conference on Kimberlites, Cape Town,
1973. 16. MOORE, M„ and LANG, A.R. Phil. Mac . vol. 25. 1973. p. 219.
7
FKAt.F ELEMENTS IN DIAMONDS
17. TAKAÍ.I. M . and l.ANO. A R r*-., K"> .V«> \ voi 281. 1964. p HO 18. FFSO_ H.W.. BIBBY. D M . SH ISO HOP. J.P.F., and WAITF.RSON. j IW. ( rjjwanaht i h,m
vol. 17. l»>74 p 1«S 19. I.K.HTOWI.FRS, F.C.. l«.i,yr I M I I I , vol. 3«. 1962 p 1398 20. LKiHTOWl.FKS r ( l « i w < hem. vol. 15. 1963. p. 1283. 21. l.KiHTOWLF.RS. K : M l l V i l \\l) IHHSOl t>l,Y Of l\lnsiKIM IV\\IO\[)S Hwh J
U',1 London. Industrial Diamond information Bure.u, 1967. p. 27 22. RANDA. / . . BFNADA. 1 . KVNUR. I . and KOl'VIMSKY, J J. raJ,ojnjiyt I hrni.. vol 14
1973 p 437 23. VANCE. E.R., HARRIS. J.W., and MILLEDO-E. H.J. Mm \Ug.. I on J vol 39 19:3 p 349 24. LANG. A.R \jrurr l.on.t . voi. 213. 1974. p. 195 25. BIBBY. D M . and RASMLSSEN. S.H. RAÍvnhem. rjJiojnjtyt iff... vol 9 1972. p 1. 26. RASMUSSEN, S.F.. FESQ, 11.W., SELLSOHOP, J.P.F.. and STFFLF. r.W. Johannesburg.
National Institute for Metallurgy. Report ni> If 6.1. 1973 27. YULE. HP. Washington, National Bureau of Standards, Sp,\ l'ub. M2 1969 p. 1108 28. HARMS. J VttW lustrum. Meth., vol 53 1967. p 192 29. BIBBY. DM., and RASMUSSEN. S.E. RjJunbem rj.i„>jnjlyi Lett., vol. 14. 1973 p. 9. 30. ZANDERS. J.A.J., BIBBY. D.M . and RASMUSSEN. S.E J I'hys t., vol. 6. 1973. p. 973 31. WATTF.RSON. 1... WATTERSON. J.I.W., RASMUSSEN. S.F... SELLSOHOP. J P F . . and STEELE.
T.W. Johannesburg. National Institute for Metallurgy, Report no 1476. 1972. 32. BiBBY, DM., SELLSOHOP. J.P.F.. and STEELE. T.W. Johannesburg. National Institute for
Metallurgy. Report no. 16.19. 1974. 33. ERASMUS. OS.. HAWKINS, DM.. KABLE, F J D. FESQ. H.W, BIBBY. DM., SF.LLSOHOP.
J.P.K., and STEELE, T.W. Johannesburg, National Institute for Metallurgy, Report no /652. (To be published).
34. FF.SQ, H.W.. BIBBY, DM., ERASMUS. O S . KABLF., F.J D.. and SEl.LSCHOP, J P F International O-nferencc on Kimberlites, Cape Town. 1973.
35. FESQ, HW., BIBBY, D M , FRASMUS. OS.. KABLF.. F..J.D.. SEL1-S0HOP. J P F . and STEELE, T.W. Johannesburg, National Institute for Metallurgy, Reynrt no 16.16. (To be published).
36. DYER, H.B., RAAL, FA., DU PREEZ, I... and LOUBSER, J.H.N. I'hil VIJ* , vol II. 1965. p. 763.
8
I RAOF ELEMENTS IN DIAMONDS
/4J»/.f. /
\eutrnm flmxet and cadmium ratios
Position Neutron flux Od ratio in cm " s i (for cobalt I
Pneumatic facility 2 -•" I 0 1 32 PooKulc facility 8 X U)' ' ' i i
1.4.81/ 2
hotopn pouttvriy identified in natural diamnndt
1 lemenf K, . | :„
niKlkir
Half -hlr i j m m i - r i ; ^ealo-* dr t r t t r t. kcV AnalvM-.
peak. kcV
Sa Ni-24 15 «I h 1 «f.H I 7 3 2 U H i 1368
M» M r 2 7 9.45 mm 11)14 844 1014
Al. Si AI-28 2,31 min 1779 12681 S I ) 757(1)1 > 1770
S S-37 5.05 mm 20H«K|)I ) 208OIDI1
(1 «.I-3R 37,3 mm 2167 1642 2167
1642
K K 4 2 12.5 h 1525 1525
<a « j -49 8.8 mm 20o2( l ) l 1 2062(l )F)
V Sc-46 83.9 «1 112(1 889 889
t a . Ti S*-47 3.43 .1 160 161)
l> Or 51 27.8 d 320 320
I I T i SI 5.8 mm 321» 929 61)8 320
V V 5 2 3.76 mm 1434 1434
Mn Mn-56 2.56 h 2113 7891 D M
1811 16021SK
84"
IJOOfSK)
109WDI •:» 1811
I T Mn-54 303 d 835 835
I T I T - 3 9 45.7 d 1292 1099 193 141 1099
1292
C> i i»-60 m 10.5 nun 59 59
(A; C.W.O 5.27» 1332 1173 1332
1173
N I 0>-58 71,3.1 811) 0* 810
Ni Ni-65 2,56 ii 1482 i n ; 1482
<u Cu-64 12.8 h 1346 a- 1346
( u C u d * 5.1 mm 103« 1039
C.a { . » 7 0 21,1 mm 104H 1048
G» C,a72 14.1 h 2202 2 Í 0 8 2202
( k Cc-75 79 mm 26S 199 26$
As Av76 26,3 h $59 657 1216 6$7
Hr Br-80 17.6 min 617 0* 617
Br Br-82 35.9 b 777 J 34 619 6 9 8 777
828 1044 1317 147$ 1044
Kb Kb-86 18,7 d 1077 1077
Sr S f -87m 2,84 h 389 389
St> Sb 122 2.75 d 564 693 $64
Sb Sb-124 «0,9.1 603
646
1691 72J 2091 1691
TRACE ELEMENTS IN DIAMONDS
TABLt. 2 ItomtJ)
Element Kadio- Hall lite l iunnu- r iy peak» * detected. keV Anatywa
nuvlide
2.07 v 605 7«6
peak. krV
a 1>134 2.07 v 605 7«6 7«6
Ba B i l M 11.3 J 496
124
374 216 134 •96
i24
•* Ba-137m 2.6 mm 662 662
Ba Ba 1)9 S3 mm !o6 l * >
La l.a-140 40.3 J 1595 816 487 329 15*5
172 242 267 432 876
751 950
867
574<I>H
919
10*4<SE>
V25 4 * 7
Ce Cf-141 32.5 d 145 145
Nd NJ-147 11.1 d 91 31V 531 91
531
Nd N.1-149 1.8 h 115 211 270 211
Sm Sm-153 47,1 h 70 103 103
Sm Sm-155 21.9 mm 104 104
Ey Eu-152 m 9.35 h 122
1315
344 842 964 122
964
Eu F.u-152 12.2 y 122 245 344 411 I 408
444 779 964 1086 1086
1408 367 1112 1299 779
344
122
Eu Eu-154 16.0 y 123
1595
723 1006 1274 1274
1006
Gd GJ-153 236 J 98 103 98
103
Cd Gd-161 3,73 mm 360 360
Tb Tb-160 73 d 87 197 216 299 879
879 966 1178 1200 299
1272 1312 309 393 1272
765 362 1003 111 ) 87
Of Dy-165 2,36 h 95
715
280 362 633 95
280
Ho Ho-166 27 h 81 1380 1382 1380
Bt Er-171 7,8 h 308 296 112 308
296
Yb Yb-169 30.6 d 64 9 4 110 1 ) 1 198
177 198 308 177
V b Vb-175 101 h 114 283 396 396
Lu Lu-177 6,75 d 208 113 208
T« Ti -182 115,1 d 68 100 152 222 1222
229
i - 2 2
264
1231
1121 1199 1231
1189
W W-187 24,0 h 686 479 134 7 Í 6 8 *
k lr-192 74,4 d 296 308 J17 46« 4o0
S M 604 612 206 296
374 416 484 7 8 Í
U lr-194 19,7 h 328 » 4 645 32«
6 4 }
10
TRACE ELEMENTS IN DIAMONDS
TABl.t. 2 Komi J)
-Element
, . Haiti»
nutltde
Half l i ft ! ! i .
Camma-rav prakt* de'ected. keV Analysis
peak. kcV
ft Au-198
Au-199 2,7 d
3 . l 5 d
1 !
Í
412
158 208 412
15«
n> Ha 2 5 ) 27.4 d j
i ! 2
)V9
34» 111 |c>4 2nH
312
i ' Np-239 2.35 d l 19
228
KM
278
106 U N l«4
106
* l>E : Double escape SE - Single eacape
TABU. 3
Hnek tumjards used
Element Standard
USGS GSP i
Value
Na
Standard
USGS GSP i 2,08 "., K USGS GSP-1 4,59 % Sc USGS BCR 1 32,0 p.p.m. Ti USGS BCR 1 12750.0 p.p.m. O USCS DTS 1 4160,0 p.p.m. Ee USC.S BCR 1 9,36 p.p.m. Co USGS BCR 1 38.0 p.p.m. Ni USC.S DTS 1 2440.0 p.p.m. Rb uses C;SP i 261,0 p.p.m. Sb USGS GSP 1 3,1 p.p.m. Cs Internal std OK227 2,05 p.p.m. Ba USGS GSP 1 1335,0 p.p.m. La USG5 GSP 1 175,0 p.p.m. Cc USGS GSP 1 320,0 p.p.m. Eu USGS GSP 1 2,24 p.p.m. T * USGS GSP 1 1,06 p.p.m. 1 m USGS GSP 1
.. ., 106,0 p.p.m. 1
11
1 RACF tl.FMKNTS IN DIAMONDS
TABIt 4
KJJH aurttJri of jijfiw/it•»»•<- fur tfiunuutwe atudysa
l*rirvip.ii l l tn ic iv . K J J I . I I I U I iulc Halt life > energies
!
\ . i Vi 2-i 15 h 1 .(.8 5 Al A; :s 2..M min ; 1779
S Mc 2 7 S-57
9.5 mm \ 844.U 1UU.1 5.(»5 min ! 5 h»2.4. 208O <DF >
CI n 58 37,5 mm ] 1642.7 K K 42 12.4 h 129J .6 Cj ( .1-49 8.8 mm 3 0 8 5 . 2572 'M- i. 2062t » 1 )
Sk 4 o 85 .9 J 8 8 9 . 2 , 1120.4 Ti
V is
11-5 I V 5 2 U S '
5.8 mm 520 3.7o min 1454 27.8 a 520,1
Mn Mn 56 2.6 h 8 4 6 . 9 . 1810,8 l e Ft 59 45,2 d 1099,2 . 1291,5 Co Co-60 m 10.5 :mn 58.5
G>-60 5.27 v 1175 ,2 . 1552,5 N'l Ni-<S5 2,6 h 1115 .4 . 1401,7
C J
Co-58 Cu-66
71.5 d J l l . O , 810 .5 5,1 mm 1059
As As-7 6 26.5 h 559.2 , 657 ,4 Rb Kb-86 18.7 d 1076,8 Sr Sb
Sr-87 m Sb-122
2,8 h 388,2 2,7 d 564,1
St.-] 24 60 ,0 d 6 0 2 . 8 . 1690,8 Cs O i l 34 2,0 y ! 6 0 4 , 6 . 795 ,7 Ba Ba-1 31 11,5 d ! 4 9 6 , 5 , 123,8. 215,•>
Ba-139 82,8 min j 165,6 U La-140 40.2 h i 1595.4 , 4 8 7 , 0 Ce Ce-141 32.5 d j 145,4 Sm Sm-153 4,7 h , 103
Sm-155 21,9 min 104 F.u Eu-152 12,0 y 344 , 779 , 964 ,2
Dy Dy-165 2,36 h 1112 . 1 4 0 8
9 5 , 280, 362. 6 3 3 . 7 1 5
Ho Yb
Ho-166 Yb-169
27 h 32 d
138Q, 1582 94 , 109, 130. 177 ,
Yb-175 4,2 d 198, 3 0 7
114, 282 , 396 Lu l .u-177 6,7 d 113 , 2 0 8 T J Ta-182 115,0 d 1121 ,4 , 1221,4 Ir Ir-192 74,2 d 316 .5 , 4 „ 7 , ? f
Au Th
Au-198 Pa-233
2.7 d 27 ,0 d
4 1 1 , 8 311 ,9
The gamma-ray energies used for quantitative determinations are underlined.
12
TKACt FLI-MFNTS IN DIAMONDS
lABlf 5
tract tirmrnn m fttmm fcwuA
w ^ f l f '%! J « o n 1 AJ i«Ji
í 1 P m
- T "
. . ( ! A " 1 1~
P1B i . i I »
P H 0 I 4 4
P:A .' : J I
P2B ,1 : 15
P2l . H 2 16
P) '1 : 4 9
P4A n ) 9 '
P4B .> t t"
P i A • « i 1 2 6
P5B ,) > 39
Pf.A t ) i M
P~ (. 4 5 :
PH
PV " 4
1
3 2 ^
1 *>
P M A
P I O B
P l i M
PI I A
PI I B
PI 2 1
PHA i PI3B 1
PI4B 1
P15A 1
PI5B 1
PI «A 1
P16B 1
P1*< i 1
PI 61) ! 1
PI7A I
PI7B 1
P17C 1
PI 71) 1
Pnmtet t
IJJ
llll
.1»*
! 1
1 " )
176
3 14V
3 7.1
1 3 )
3 4 2 0
3 176
1 1 7 |
3 •• 3 S 2
) I 23« i 1 276 > ! 1V6
J 1 5 2
i 9
2 1
9 9
2 ()
2 ,7
0 . 4 7
I B
11.71
2 . 0
0 . 6 7
0.57
I I S
1.35
I I 7 9
2 . 2
I I
1.45
1.15
0.91
p p m .
Al
ppm p p b. p p m : p p m
Í:
p p m P P f c
. t o ; * 1 I.M 0 . 2 4 17 0 O i l O.OM : o « »
0 . 2 4 1.4 0.5«) 3 2 . 0 1 « 0 2 1 i 0 . 0 4 i - 5
0 . 1 5 5 4 4 7 2 5 . o 1 2 1 9 0 . 0 9 ; 6 . o
I I I » * 0.2V 0 . 2 3 2 6 . 0 0 4 7 »> IÍB ! o . o j •' 2 .5
11.055 O 14 . « 1 2 2 3.0 O . I O O .OI ' 0 . 4 5
o n 0 4 1 0 37 2 4 . 0 0 . 4 O O.09 , 0 .O4 l . o
i n » 2 5 .1 17 » 6 . 0 O . I O 0 . 2 ) 0 . 0 i 0 . 0 3 0 . 9
0 . 7 » I I . ' i 11 • 4 7 3.» • o .25 \ 9 0
l « l 8 " 5 4 I S O 0 12 4 5 i n 0 .1 7 1 5 . 1
0 34 9 i lo.o t » . r . 3 9 6 . 4 O l ? • B O
0 . 6 4 1 . " 2.7 4 0 0 2 3 0 . 6 4 0 , 0 6 j 5 .0
( i i : 5 4 4 .5 2 0 . 0 I ' M 5 1 1.4 0 0 7 < 5 . 0
0 . 1 4 2 4 2 7 6 6 0 0 . 0 5 1.» 1 2 0 . 0 « i ''' 4 4 47 0 14 7 9 3 0 . 0 1 1 7 2 5 o '.» • 2 .0 ' 45 0
2 0 14 O 7 o 6 4 . 0 0 3 4 12 o 2.7 0 1« ' 46.11
J I 0
24 n
74.''
36.11
30 ,0
14 ,0
21.11
45 0
53.11
14,0
26. I I
9 3 , 0
75,0
4BO
1 2 « 0
75.0
6 5 . 0
5 6 . 0
6 7 . 0
2 3 . 0
6,2
I 2
II o
28 11
; 5,1
5.v
; Í 6
7,5
6.1
; ' I . *
14.4
10.»
15.7
».» 9 . 0
« 7 I I
1 5O0 0
I 30 11
4 T O O
1 B 7 I I 0
2 3 O 0
5«,0
3 9 . 0
1 0 0 0
4 * 1 1 1
1 6 0 . 0
5 2 0 0
6 7 0 0
2 4 0 . 0
3 * 0 . 0
3 4 0 , 0
1 4 1 0 0
450 .0
11.92
11.9«
1 3
o 44
1 1
I I 2 9
0 . 7 »
I I B6
O 2 0
0 . 3 0
0 , 9 3
! I-**
i ' "' i I II I
0 , 9 7
I I
3 ,6
2 7
3 5
15 0
12 o
57 O
9 2
1 2 o
2 . 2
15 o
22 o
9 6
6 4
S.2
4 3 O
9 3
I I
5 0 . 0
10.11
I 1 .0
I 1 2 . 0
i 5 .6
m . 6
3.1
2 2
0.41
5 1
1 2 0
1.55
1 «
2.7
5 5
2.6
1 7
2 ,9
1.7
2 .9
2,1
2 .2
1 1 . 0 4 4
0 , 4 2
0 , 5 0
2 6 9
0 4 4
0 . 4 1
0 14
| 0 6 *
• 1.02
í 0 . 3 2
I 0 , 2 5
! 0 . 2 2
7.4
0 .B4
0 , 6 5
6 »
2 .6
o . « j
1 , 0 )
17,11
2B.0
I40..1
22.1»
22 ,0
5 5
57 o
41 II
2 ) 0
I III
9 5
56.11
4 4 , 0
2 ) 0
M i l
2 2 . 0
3 6 , 0
2 9 . 0
1 9 , 0
0 . 4 4 3 B O
N i l
? V O
21 o
I 2
0 . 6 6
9 ,2
72.11
I lO .O
1 2 o . l i
21 o
290 0
« I I
117 O
2IOO
" I I I
21 o
1 5 o o
2SO.i l
121 O
160 16.11
2 3 0 0
20»t,o
I 6 ) 1 1
p p h .
I ! ) 6 , o
j 21 O
! *> . •
; * 7
) 4
; 1 0 . 2
I 25».o • 11 4 O
i 2 0 « o
! 17 O
! 9 7 . 0
6 4 . 0
5 2 0 . 0
! 2 l O . O
2 l o . i l
2 l o . o
12BOO
2711 o
205 o
»1 ii
157 o
6J1I.II
• l o o
I 1250 ; I M l »
» 2 < M >
2 5 O . 0
4 O O . 0
2 JO o
3 t o o
0 «
4.5
» 2 7
0 . 1 5
0 . 2 ?
O 54
1 1 2
6 5
15 4
2,4
imO.O 3 2 O 0 I B . I
12 o
2 5
22.11
13 o
1 4 O
« S O
21 o
2 4 . ! !
45.11
I J O
4 2 . 0
> » o
1 2 . 0
p p l >
7 .»
1.2
3 6
J O
22 0
1 ! o
6 ?
15 0
5 7
4 . 6
m o
36.11
i : o
?4 .1
1911
10 0
I ' l l
19.11
15 o
59.1
I70.O
16 ,0
3 9 o
1 * 0
1 5 ) 0 . 0
4 2 0 O
2 4 , 0
o IV
o.o2 0 0 4
1)1»
0,14
O.07
i :
III?»
o n
o 12
o . i r
0 6 1
. 1 6 4
1 1
I l"6
0 6 9
0 » 6
1 1 1
I 19
0 6 1
( 1 4 )
o 5 5
0 55
1 HI
O.B6
I.?
1.2»
0 4»
1 ) 7
4*.o
1 4 4
p » b •»*
I 3 4 0 . 0
7 30 0
1 2 0 0 0
2 B O O
6 2 o
4 5 0 0
ixm.o 9 5 0 O . 0
«nu.o JJO.O
2 4 0 0
DOO.O
» 4 0 . 0
170 .0
O . O I )
0 . 1 » )
0 , 1 1
0 0 9 *
0 . I M 2
0 , 7
0 ) 4
0 , 0 *
0 . 1 9
O.044)
0 . 0 5 2
0 0 2
O . O I
0 . 7 )
» 1
0 . S 7
1 1 . 9
O . O M
1,21
1 » )
0 2 >
M>
. p b
» 9
5O.0
2 6 0
2 O . 0
1 2 7 . 0
1 ) 6
14.6
10.1
2 5 . 0
H.O
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IKM.I ELEMENTS IN DIAMONDS
15
l'KAt'.F. ELEMENTS IN DIAMONDS
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I RAO ELEMENTS IN DIAMONDS
TABIt V
Drtjy time after uhich the isotopes were .left tr.l M,intUrJ\. .mJ Jetrct urn hwiti
I >.-.. . '• t l l ' K -, .._ |
l ->"T« '«)- *>u « I | 7.1 u : :; ! 5 » ! l > . ' , . - . , . - S i i m l i r l
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1 . 5 i • ...,': 1 I K ;
\ - 5 2 • ' o • M m : V - ( ) • M \ ( > , « . . i n
i « 1 ' • • . . , » > , , ; H h !
M i l * ' • • • I l l M i ' l Mn U N O . « . ' ' I I
1 . V < * • • H | l « HI K I
( . , o l l m U . I K I 5 ( n l M P i i « « . . i n
1 t> f * l • • ' I M N M 5 BCK ; ' . 6 « • ( > . 7 N i l N O , i ; « J l i l i
( ,.-5Hl V I • • . I I U\ [> IS 1
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M 87m • 11.(11 S n N O , i .
M . 1 2 2 : • • 11 1H H I 1 (,SP 1
V ^ I 2 t • • O.O0O0I ( .SI ' 1
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<.<-Ml t f • • • t',(MMK)5 GSP 1
Nni-15 < ' • ( 000005 S m j i w i i h
Sm-I 55 ' I U H K X I 5 S m . i N O i ) ,
Hi-152 • • • 0.000002 (iSP I
1 * 1 6 5 • 0.00001 D y 2 < \ 0 , > ,
Mo 166 ' 0.000005 H o , ( N O , ) ,
M i 169 • * 0.0001 V h j I N O j ) . ,
VI. 175 • <(.0OI)l V l i 2 ! N O . | ) ,
I n 177 • • 0.00000$ I . i i . l N O i l )
I i 1X2 • * • 0,0000$ GSP 1
Ir 102 • • • 0.0000005 <Nll4>jlrC:l A <oln
An 108 * 0.0000005 NH4A11CI4
P i 2 » J ( i h » t '
• 0.0000005 GSP 1
t Interference found - see feat.
Jf, - Counting lime.
17
'H , B*P*ï8fFW£PP* t"^íWa*iP" i&
Oamma-ray paah M9 k«V Actual harf-lifa «3,90011 Mcourad hatfltfa 86.000d
0,00 40,00 »0,00 110,00
OAVS
•JN l«,M 14,00 32,00 40,00 40,00 U.00 (4,00 72,00 DECAY T I M E , d
00,00 M,00 M,00 104,00
F I G U R E 1 Decay curves for scandium 46
7/,00 «0,00 (1,00 9*,00 104,00
F IGURE 2 Decay curve (or lanthanum 140 and iridium 192
to* Gamma-ray peak 406 k*V Actual hwMifa 11.300 d Maaturwl h.ilf lif» 11.500 d
S
I
14,00 ERROR VS DECAY
» '
Í * # • '
tjm M , W 40,00 «0,00 DAYS
> W
Z
0,00 I I I I
1,00 «,00 ït,oo »,00 40,00 (»,00 s«,oo OCCAY TIME, d
«.,00 71,00 »0,00 • »,00 »(,00 104.,00
FIGURE 3 Decay curve for barium 131
•s
>
$00 DECAY I I H E , s
1000
FIGURE 4 Decay curve for vanadium 52
TRACK ELEMENTS IN DIAMONDS
A P P E N D I X
A SUMMARY OF THE PREVIOUS WORK ON NATURAL DIAMONDS
The literature survey carried out for this project collected much of the previous analytical data obtained for diamonds, and Table II gives a summary i.f this, together with the results obtained in this work. It thus provides a useful comparison with the results of the present work The rarlv work of Wagner1 and Williams* has teen omitted because thev could anaksc only t ie ash obtained from the combustion of Uurr stones containing extremely high concentrations of impurities Mn» approach is understandable when the sensitivity of the analytical methods avat. :t>le to them is realized It is of interest to note the emphasis on neutron-activation analysis both for qualitative measurements (approximately 60 per cent of ail elements detected) and for quantitative determinations (approximately 80 per cent of all the results). If only the data obtained since 19o3 arc considered, these figures are both greater than s»0 per cent This shows, probably more clearly than in any other way, the acceptance of neutron-activation analysis as the preferred technique for the analysis of diamonds Although the values given for the various elements cover wide ranges, occasional results are extremely high compared with the other values reported These may be due to contamination, or to the use of unsophisticated cqu.oment One example of this is the gold value of 20 p.p.m. reported by Krccdman' This was the first /".ample of neutron-ac'ivation analysis applied to diamonds, and the very high result may have been due either :o the crude equipment available to him, or to contamination (e.g.. as a result of cleaning in platinum gold laboratory ware) In addition, the results given by only one laboratory must he considered suspect until confirmed te.g . for hafnium and mercury4), and the presence of relarivrly complex organic compounds is surprising in view of the extreme conditions in which diamonds form . However, it must be appreciated that in the extreme all elements can be potentially found in diamond, that all diamonds arc different, and that widely differing concentrations of elements can be expected.
In the future it is certain that more elements will be found in diamonds by the application of existing and new methods of analysis. It can be expected that more effort will be applied to the determination of the position and variation of impurities within single diamor Is, and in the use of the results to gain an understanding of diamond growth and the conditions existing in the Earth's upper mantle.
22
I'RACE ELEMENTS IN Dl WIDMiS
ÊAHIt I •
1 Mimm.try nl \<nnr •liment\ JO./ ïiimpnuiith ,/fttv'i -.' .in.I mr.nuir.i in .tijinnn.h
—"^—————— 1 íe*m*nr
Kef r r r m r M r i M - r r : •. j i n i " . I t - . - • • - ' i : - ' - -
• " • • • p o u n d i 1 Vs t , , , « i . r k i •i'»-'. range1»
- -.. <pp HI un;r-\c of ..TUiNC \ h o w n >
I I - f. Ms
Í ,
I M ) S r. MS
H H •! OS
111 OS
( () ? f MS
( (), 5 MS
i l l , "» MS
( ; I ' . s M -
( , 1 1 , 5 MS
( l l , l I f . O i l s Ms
\ 5 MS
( i 2 3 0 0 MS
I D ! 5 < H I Jo 2Not) I'A
1 ! i M i n i l » ( I ' \
1) 12 1 V V \
1 .V 1 W 11 in iron 1 N \ A
\ . i 8. 14 OS
15. 1«. N A
4 0.73 t<. : o . o \\\ i 7 NT) to 34 N A
If» 0.0O4 t o 4.2 N A
1« 11.05 to (1,4 N A
l \ \ 0.OOÍ t o K.I N A
MU H. >>. 14 os 7 4 i »
i n 7 ro iV> N A
I H 30 N A
2 0 N'l) t o 1 5 OS
21 0.1 t o 3 o (" rw 0 , 0 4 to 37(1 N A
A l H. « . 14 OS
15 , U N A
7 10 OS
1 1 0 . 0 6 to 1,04 N A
I f . O.Oo to 9,1 N A
18 0 ,4 t o 1 0 0 N A
?() N O t o 8 0 OS
21 21 0 ,04 to 3 OS
2 3 23 0,1 t o 2 0 N A
2 4 0 ,2 t o 8 0 N A
rw 0 , 0 2 t o 6 5 N A
23
I RACE ELEMENTS IN DIAMONDS
lABIh 1-1 teont.ii
" Element Reference Measure»! values Technique c o m p o u n d ! TW - this n a r k ) j m i ringn
(p p m unless otherwise shown)
Si 8 . 0 . 14 OS 7 80 OS
20 NT) t o 50 OS
21 0.05 to 40 OS
S In v\ TW 10 to *>0 NA
CI 16 NA
rw 0,013 to 3,6 NA
Ar 5 MS
K 16 NA
4 Nl) to 48 NA
rw 0.01 to I » NA
Cn «. 9, 14 OS
1'. NA
- 1(H) OS
20 ND to 20 OS
21 0,1 t o 0.8 OS
•rw 0,025 to 195 NA
Sc 4 0,32 to 2 8 0 p .p .b . NA
' 6 0.04 t o 8 ,96 p .p .b . NA
1H 0,54 to 52 p .p .b . NA
25 0,001 to 0 ,4 p .p .b . NA
TW 0 ,004 to 18,6 pp.1). NA
Ti 0, 14 OS
16 0,5 t o 3,7 NA
18 1.8 t o 5.0 NA
20 ND to 8 OS
26 0.06 OS
rw 0,005 to 29 NA
V 16 0,3 t o 64 ,3 p .p .b . NA
V 0,06 to 2 6 0 p .p .b . NA
Cr 14, 20 OS
4 0,03 to 2 1 5 NA
7 20 OS
16 0,005 to 6 ,07 NA
17 0,073 to 144 NA
18 0,08 to 1 0 0 0 NA
25 0 ,0004 to 0 ,09 NA
TW 0 ,0005 to 6,6 NA
24
IKA< r. I IE MEN IS I s |>| \.MONI>s
I AMI II <ïonl.l>
I lenient Keteren. •: Measure,! '.alues 1 c h n i q u c
u i m p o u m l ! I W trus « . , r k | <in<i r inses
i p p ni un.css otherwise shown >
Mn '» OS
15. 1'. NA 4 0.O43 to 3.* NA 7 1 OS
17 - 0.0OO1 !,. 3.2 NA IK o oo2 5 !,> 2.5 N \
19 i i . i ) 0 2 t , i i i . i i ' ) NA
IW o .ooo? t,, 5.4 NA
l< 8, " . |f, OS 7 200 OS \t> 0.2 r.> 20.7 NA
2o Nl) to" 30 OS
21 0.03 to 7 OS TW 0.07 to 141) N \
( i> 9 OS
4 0 .0034 to «..4 NA If. 0.DOD3 to D.254 NA 18 0 .054 to 11.77 NA
25 0 .0005 to 1,5 NA TW 0 . 0 0 0 3 to 1.5 NA
Nl Id NA 7 80 OS
25 0.02 to 4«) NA
rw O.o25 to 46 NA
Cu 8, 14 OS 16 NA 7 40 OS
17 0 ,0005 to 4 0 NA
18 O.O50 to 2 ,9 NA
19 0 ,0004 to 0 .9 NA
20 Nl) t o 8 OS
25 0 , 0 0 2 6 to 1,1 NA
rw 0.001 to 15 NA
/ n 9 OS
( , i 4 NA
16 NA
rw NA
(ic 16 NA
As 16 NA
TW 0,001 to I t , 9 p . p . b . NA
Br 16 NA
25
TRAlF FLF.MFVrS IN DIAMONDS
M M f M i.„Ht.f)
Kiement c o m p o u n d
! i i
i
Rcteren i TW this vvorkl
Kb 1 r>
IW
Sr 14 4. 16 I\V
Zi
A* 9. 14 4
Sn 9
Sb 4. li» 25
C.s
Ba
l.a
TW
1(. 4 TW
14 4 16 TVV
16 4 17 18
25 TW
Cc 16 4 TW
Nd 16
Sm 16 4 25 rw
F:U 4 16 TW
Measured values Techn ique
and ranges i p p . m unless otherwise s h o w n )
| | NA
0.001 to 0 .127 i
t
N A
O S NA
O.0O7 to 2.4 p .p .b .
I
NA
NA
OS
0 ,035 to K.l ] NA
30 1
j O S
O S
NA
0,05 to 4 p , b . i NA 0.02 to 350 p .p .b i
NA
NA
0 ,0039 t o 0 ,017 ' NA
0 ,041 to 5.6 p . p . b . NA
OS
2,4 t o 58 NA
1,0 t o 18,5 NA
0 ,007 to 20 NA
NA 0,01 to 14 NA
0 ,0015 t o 0,94 NA
1,4 t o 3,o NA
0 ,00002 to 0 ,001 NA 0 ,00001 t o 0 , 1 2 4 NA
NA
0 ,014 to 16,8 NA
0 , 0 0 0 0 5 t o 0 , 2 3 0 NA
NA
NA 0,15 to 500 p.p.b. NA
0 ,004 to 0,25 p.p.b. NA
0,01 to 25 p.p.b. NA
0 ,12 to 97 p . p . b . NA
0 , 0 4 to 5,48 p .p .b . NA
0,001 to 3,6 p.p.b. NA
26
TRACK FLF.MENTS IN DIAMONDS
IABLK II (comtdl
F.lement/ Reference Measured values Technique c o m p o u n d ITW rh i i work l and ranges
1 (p .p .m unless o therwise shown)
K.U i 4 0,12 t o 97 p .p .b NA
l o 0 ,04 to 5.48 p .p .b . ! NA | TW 0 ,001 t o 3.6 p p .b . NA
( .d Í 1 " NA
Tb 1 16 0 .06 to 0 ,98 p .p .b . NA
'>> 1
l o NA 4 0,27 NA
| TW 0 ,03 to 4.7 p.p.b. NA
l l o rw 0.01 t o 1,5 p p . " . NA
Fr 16 NA
Yb i- NA 1,5 t o 8 ,2 p . p . b . NA
, T W 0 , 1 6 to 3,0 p.p.b. NA
l.u ! «6 NA 4 0 ,76 to 3.0 p .p .b . NA TW 0,01 to 0 ,65 p p .b . NA
l lf 9 OS 4 0,5 to 86 p . p .b . NA
Ta 4 NA 16 0 ,4 to 1,6 p.p.b. NA TW 0 , 0 6 6 to 33,0 p.p.b. NA
W 4. 16 NA 25 0 , 0 0 9 to 0,6 p.p.b. NA
Ir 4, 1 6 NA 25 0 , 0 0 0 6 to 160 p.p.b. NA TW 0 ,0005 to 37 ,0 p.p.b. NA
Pt 9 _ OS TW NA
Au 16 NA 3 2 0 NA 4 0 ,05 t o 65 p.p.b. NA 18 0 , 0 7 2 t o 5,4 p.p.b. NA 25 0 ,001 to 0,1 p.p.b. NA TW 0,001 t o 0 ,37 p p.b. NA
H» 4 0 , 0 0 4 t o 5,4 NA
to 9, 14 - OS
27
TRACE ELEMENTS IN DIAMONDS
r ,4S l . f II (contJ)
Element Reference Measured values • echmqjc compound ITW = this work! and ranges
(p.p.m. unless otherwise shown*
Th 4 0,77 to 70O p.p b \ \ r\\ O.f) to 29 p.p b. NA
t' 4 V \ TW NA
LEGEND
MS Mass spec t romet ry
G Gravimetric
KNAA Fast neutron-act ivat ion analysis
OS Optical spec t roscopy
PA Photon act ivat ion
CPA Charged-particle activation
NA Neutron act ivat ion
Indicates qualitative de te rmina t ion only
ND Not de tec ted (optical spec t roscopy general ly)
p .p .b . Parts per billion ( l O 9 )
2«
TK \ ( ^ H I - M I M S !N DIAMONDS
R E F F K F M ES
1 W'AGNF.R. P \ |lu- di.mi.irul l i r ids of Southern \ t r i ca Cap,- | , , . A r , ( s m i i k I ->!, I « " l
- Wll I IAMS \ I | ' i f ^cnt-si-. nt the d iamond London, I Benn I t . : 19<>
-' I K F F D M A N N s / .(.,•..-:. « . . . s . voi 20 1952 p l"4( l
•* K \ N D A . / , K I N A D V | M N C I R . | . and K O I A T M S K V J ; , , , . . „ • , • , - . . .,' • + i*>7» p 4<r
5 M F L I l - N ( I arid ! . t \ K I ) l \ | . \ A. Personal Conimunciatu , ! : 19"4
" KAIM K. \\ . ami BOND. W [.. / • , ' v «.•: . v.,- | | 5 1959 p K,-
" \ N ( . l S. J ( . Wll I li A . and S I A N K O . W S . ./ j / . ; , / ' / • - , , . m . J 9 ! 9,,« r 1915
H Bl NI INf , . I M and VAN V A I . K E N B l ' R G . A I . , , , - \lr-i vol 4 3. 195H p 1"2
9 S 1 R A I \ 1 \ N I S . M l and AKA. F / / \<;,-r , / , - „ . s „ . . v,,! 73 1951 p 5^43
""• ROCCO. ( . ( . . ( . A R S O N O.I. . and C.M.I. ) \> h,- / , , , , , ; « . , . , , , - Is. < , , „ - . u . < | - I9r,r,
p 433
11 S H . I . S M I O I ' J.P.I- . HIBBV D M . FRASMCS, I V, and M I V . A Y . I) » . D u m o n d R e w a r d
1974 Industrial Diamond Div tnbu to . s , London 1974 . p 43
12 KIBBY. I) M. and SI I I Si HOI'. J PI- I rjj„,j„jiv, , /,, „, U ) i 1 2 l<>74 p UK
13 BIBBV. D M . SFI .LSCHOP J.P.I . and S I F F L F , T W Johannesburg . National Inst i tute tor Metallurgy. H-pi>n m, / o f / . 1974.
!4 ( I I F S I I Y . I ( . \„„- II..,,-. vol 27 1942 p 2o
15 I.OOS. K , IAEA SYtiiinar Product ion and use ot short lived ivtopcs in reactors . 5th to 9 th Nov
1962 vol 2. 1963 p 45 .
l o I I SQ, II W.. BIBBV. D M . SFI .LSCHOP J P I and WAÏ 11 KSON. J I W / , ,.l,,.„;,,,, • , / • , , „
vol 17. 1974. p 195.
17 k O H O C H N U . O V , H.N, U A / U N O V . M P . ORI .OV. Vu. I . , and SPIKVN, V I . . I>,k, U.,,i.
\juk. S.SSK.. vol 171 |9f>6 p. 107
IS < . | . . \S l NOV. M P , K O B O Í H N K . O V . P N , a n d O R L O V . Vu I. Is •„,,,„ • „ , , , , , , . V l > ; ? | 9 n 7
p. 231 19 I .K .MTOWI. IRS . F..C. Wir/y/ t >;,» . vol 35 1963 p 12K5. 20 K A A I , I A I w r \U» ,. vol 42 1957 p 3 5 4
21 GNEVl . 'SI IFV. M A., and KRAVTSOV Va. M Ih.lk \k.U. Vir.* SSAK.. vol 130. I 960 p . 154
22 C O L L I N S . A T . , and WILLIAMS, A.W.S. / l-h\s , . , V l . l 4 1 9 7 ; p 1 7K9
23 . I .U .MTOWLFRS. E (. \;Myr ( / , » ; . . vol. 34 . 1962 p 1398,
24 SOBOI.EV. N.V. . II.IN. V . G I L B E R T , F.I . and I .FNSKAYA, S.V s . n r , I'hys Solul S,.w. vol 11 . 1969. p . 200
2 ; LIGFITOWLERS. F.C. SCUM I A\[) ll(ll\OK)(,) <)l IMHSIKIM. 1)1 \UO\DS Hurls J
il'J.) Ixindon Industrial D iamond In format ion Bureau. 1967. p. 27 .
26 SOBFLOV, N.V.. I A V R E N T F . V . Vu. (. , POKHILENKO. N.P.. and USOVA, L.V , Cnmr Mm,-r,,l 1',-tml. vol 4 0 . 1973 . y. 39.
IIG/NRH
20.J.1975
2?
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