MCC www.mccgeoscience.com Diamond Morphology Diamond Morphology Tom E. McCandless Tom E. McCandless MCC Geoscience Inc. MCC Geoscience Inc. North Vancouver, BC, Canada North Vancouver, BC, Canada [email protected][email protected]www.mccgeoscience.com www.mccgeoscience.com SRK SRK – 1 November 2013 1 November 2013 MCC www.mccgeoscience.com Mine Mine grade, grade, cts/t cts/t Helam Helam 15 15 Argyle Argyle 6 Diavik Diavik 3 Jwaneng Jwaneng 1.4 1.4 Venetia Venetia 1.2 1.2 Ekati Ekati 1.0 1.0 Finsch Finsch 0.8 0.8 Orapa Orapa 0.7 0.7 Premier Premier 0.4 0.4 Williamson Williamson 0.2 0.2 Letseng Letseng 0.02 0.02 (five carats = one g/tonne) (five carats = one g/tonne) ‘Lesotho Promise Lesotho Promise Lesotho Promise Lesotho Promise’, 603 carats; , 603 carats; , 603 carats; , 603 carats; $12,000,000 uncut; $12,000,000 uncut; $12,000,000 uncut; $12,000,000 uncut; $20,000,000 after cutting. $20,000,000 after cutting. $20,000,000 after cutting. $20,000,000 after cutting. (mine (mine (mine (mine ‘grade grade grade grade’ = 4 ppb) = 4 ppb) = 4 ppb) = 4 ppb) ‘Lesotho Promise Lesotho Promise Lesotho Promise Lesotho Promise’, 603 carats; , 603 carats; , 603 carats; , 603 carats; $12,000,000 uncut; $12,000,000 uncut; $12,000,000 uncut; $12,000,000 uncut; $20,000,000 after cutting. $20,000,000 after cutting. $20,000,000 after cutting. $20,000,000 after cutting. (mine (mine (mine (mine ‘grade grade grade grade’ = 4 ppb) = 4 ppb) = 4 ppb) = 4 ppb) Large diamonds are very rare Large diamonds are very rare Large diamonds are very rare Large diamonds are very rare Large diamonds are very rare Large diamonds are very rare Large diamonds are very rare Large diamonds are very rare MCC
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MCC Diamond Morphology...MCC Octahedral Surface Features serrate laminae are sharp points and shield laminae are blunt points trigonal pits, usually negative orientation, can be flat-
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$20,000,000 after cutting.$20,000,000 after cutting.$20,000,000 after cutting.$20,000,000 after cutting.(mine (mine (mine (mine ‘‘‘‘gradegradegradegrade’’’’ = 4 ppb)= 4 ppb)= 4 ppb)= 4 ppb)
Large diamonds are very rareLarge diamonds are very rareLarge diamonds are very rareLarge diamonds are very rareLarge diamonds are very rareLarge diamonds are very rareLarge diamonds are very rareLarge diamonds are very rareMCC
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There are two primary forms of diamond- the cube and the octahedron.
Cubes and octahedra are modified by resorption of the Cubes and octahedra are modified by resorption of the primary forms, and is often called a dodecahedron, primary forms, and is often called a dodecahedron,
dodecahedroiddodecahedroid, or rounded dodecahedron, or rounded dodecahedron
It is correctly called the It is correctly called the tetrahexahedroidtetrahexahedroid..
Relation of Octahedron to THHRelation of Octahedron to THHRelation of Octahedron to THHRelation of Octahedron to THHRelation of Octahedron to THHRelation of Octahedron to THHRelation of Octahedron to THHRelation of Octahedron to THHMCC
Corners and edges dissolve like ice cubes in a gin and
tonic.
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Clear remnant (111) surfaces and textured resorption surfaces.
Partially resorbed diamond in Partially resorbed diamond in Partially resorbed diamond in Partially resorbed diamond in Partially resorbed diamond in Partially resorbed diamond in Partially resorbed diamond in Partially resorbed diamond in kimberlitekimberlitekimberlitekimberlitekimberlitekimberlitekimberlitekimberlite
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Superior Minerals Superior Minerals Superior Minerals Superior Minerals Superior Minerals Superior Minerals Superior Minerals Superior Minerals –––––––– 1981 1981 1981 1981 1981 1981 1981 1981 MCC
Derek N. Robinson, 1979, Surface Derek N. Robinson, 1979, Surface Textures and Other Features of Textures and Other Features of Diamonds, Ph.D., University of Diamonds, Ph.D., University of
Cape Town, Cape Town,
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171 Images scattered over 72 pages171 Images scattered over 72 pages171 Images scattered over 72 pages171 Images scattered over 72 pages171 Images scattered over 72 pages171 Images scattered over 72 pages171 Images scattered over 72 pages171 Images scattered over 72 pagesMCC
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Cubic surfaces are often more susceptible to resorption than octahedral surfaces.
Under extreme conditions, hillocks become completely subdued and a glassy surface results.
low relief surface
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Lamination lines are evidence of structural dislocation of the diamond crystal.
Unrestricted Surface Features (early)Unrestricted Surface Features (early)Unrestricted Surface Features (early)Unrestricted Surface Features (early)Unrestricted Surface Features (early)Unrestricted Surface Features (early)Unrestricted Surface Features (early)Unrestricted Surface Features (early)MCC
Lamination lines appear as ‘ruled shadows’ on THH.
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Forms late in the resorption process. Common on diamonds from deeper in the kimberlite and/or from dikes and sills.
Unrestricted Surface Features (late)Unrestricted Surface Features (late)Unrestricted Surface Features (late)Unrestricted Surface Features (late)Unrestricted Surface Features (late)Unrestricted Surface Features (late)Unrestricted Surface Features (late)Unrestricted Surface Features (late)MCC
also develop on diamonds.also develop on diamonds.
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3. Microdiamonds exhibit the 3. Microdiamonds exhibit the
same crystal forms as same crystal forms as
commercialcommercial--size diamonds size diamonds
((macrodiamondsmacrodiamonds).).
4. Microdiamonds in kimberlite 4. Microdiamonds in kimberlite
are mostly octahedral shapes.are mostly octahedral shapes.
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5. Whole microdiamonds have 5. Whole microdiamonds have
morphologies and surface morphologies and surface
features consistent with features consistent with
derivation from xenoliths.derivation from xenoliths.
6. Microdiamonds are not 6. Microdiamonds are not
phenocrysts in kimberlite.phenocrysts in kimberlite.
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5. Microdiamonds 5. Microdiamonds in theoryin theory may may
be preserved in cooler carbon be preserved in cooler carbon
saturated regions of the saturated regions of the
ascending kimberlite.ascending kimberlite.
6. Microdiamond growth during 6. Microdiamond growth during
kimberlite ascent is unlikely to kimberlite ascent is unlikely to
contribute mass or numbers to contribute mass or numbers to
the micro population. (FC)the micro population. (FC)
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Classification by Surface FeaturesClassification by Surface FeaturesClassification by Surface FeaturesClassification by Surface FeaturesClassification by Surface FeaturesClassification by Surface FeaturesClassification by Surface FeaturesClassification by Surface Features
include naturallyinclude naturally--occurring occurring
fragments, that are fragments, that are notnot from from
sample treatment.sample treatment.
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�� Commercial diamond contents are low in kimberliteCommercial diamond contents are low in kimberlite
�� To assess commercial diamond potential, 100To assess commercial diamond potential, 100’’s to s to 1,0001,000’’s of tonnes of kimberlite would have to be s of tonnes of kimberlite would have to be treated.treated.
�� Smaller diamonds occur in greater abundance in Smaller diamonds occur in greater abundance in kimberlite, so smaller amounts of kimberlite (10 to kimberlite, so smaller amounts of kimberlite (10 to 100100’’s of kilograms) could be treated, with commercial s of kilograms) could be treated, with commercial potential projected from the smaller stones. potential projected from the smaller stones.
The prediction assumes that: The prediction assumes that:
(1) microdiamonds will be present in a kimberlite;(1) microdiamonds will be present in a kimberlite;
(2) the microdiamonds are genetically related to (2) the microdiamonds are genetically related to the larger commercialthe larger commercial--sized diamonds; sized diamonds;
(3) microdiamonds are not broken during their (3) microdiamonds are not broken during their recovery from the kimberlite.recovery from the kimberlite.
MCC SFD Plots SFD Plots SFD Plots SFD Plots SFD Plots SFD Plots SFD Plots SFD Plots –––––––– Kicks and DropKicks and DropKicks and DropKicks and DropKicks and DropKicks and DropKicks and DropKicks and Drop--------offsoffsoffsoffsoffsoffsoffsoffs
higher plot = more stonesflatter slope = bigger stones
The largest uncut stone, 616 carats, is riddled with inclusions.
and so does qualityand so does qualityand so does qualityand so does qualityand so does qualityand so does qualityand so does qualityand so does qualityMCC
The The The The The The The The ‘‘‘‘‘‘‘‘ScienceScienceScienceScienceScienceScienceScienceScience’’’’’’’’ of Diamond Valuationof Diamond Valuationof Diamond Valuationof Diamond Valuationof Diamond Valuationof Diamond Valuationof Diamond Valuationof Diamond ValuationMCC
Diamond valuation is not a science, but does operate on a combination of scientific principles, historic methodologies, and ‘field’ experience.
Diamond valuation is not a science, but Diamond valuation is not a science, but does operate on a combination of does operate on a combination of scientific principles, historic scientific principles, historic methodologies, and methodologies, and ‘‘fieldfield’’ experience. experience.
DTC screens are based on hole assignments created in Kimberley, South Africa in the late 1800’s. DTC screens are based on hole assignments created in DTC screens are based on hole assignments created in Kimberley, South Africa in the late 1800Kimberley, South Africa in the late 1800’’s. s.
Today, DTC screens are also used mostly for sizes less than 0.66 carats in mass. These are size divisions except for +11 DTC which is a mass division.
Today, DTC screens are also used mostly for sizes less Today, DTC screens are also used mostly for sizes less than 0.66 carats in mass. These are size divisions except than 0.66 carats in mass. These are size divisions except for +11 DTC which is a mass division.for +11 DTC which is a mass division.
Stones above 0.66 carats are further divided into grainer (gr.) and carat categories (ct.) according to weight ranges. Stones above 0.66 carats are further divided into grainer Stones above 0.66 carats are further divided into grainer (gr.) and carat categories (ct.) according to weight ranges. (gr.) and carat categories (ct.) according to weight ranges.
Within the market, DTC screens also differ slightly from Antwerp screens, adding to the confusion. Within the market, DTC screens also differ slightly from Within the market, DTC screens also differ slightly from Antwerp screens, adding to the confusion. Antwerp screens, adding to the confusion.
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Diamond Value in a ParcelDiamond Value in a ParcelDiamond Value in a ParcelDiamond Value in a ParcelDiamond Value in a ParcelDiamond Value in a ParcelDiamond Value in a ParcelDiamond Value in a ParcelMCC
As a general rule, 80% of the value of a ROM parcel is contained in 20% of the total weight. As a general rule, 80% of the value of a ROM parcel As a general rule, 80% of the value of a ROM parcel is contained in 20% of the total weight. is contained in 20% of the total weight.
80% of the value80% of the value80% of the weight80% of the weight
Assume 80% of the value of a ROM parcel is contained in 20% of the total weight (don’t look at the -11 DTC’s in detail).
For ROM parcels exceeding ~1,000 carats, there is usually ten times the total number of stones.
For 1,000 carats, there are 10,000 stones total. Twenty-percent of which are +11 DTC (200 stones).
Two hundred stones for classifying into:
Assume 80% of the value of a ROM parcel is Assume 80% of the value of a ROM parcel is contained in 20% of the total weight (doncontained in 20% of the total weight (don’’t look at t look at the the --11 11 DTCDTC’’ss in detail).in detail).
For ROM parcels exceeding ~1,000 carats, there is For ROM parcels exceeding ~1,000 carats, there is usually ten times the total number of stones. usually ten times the total number of stones.
For 1,000 carats, there are 10,000 stones total. For 1,000 carats, there are 10,000 stones total. TwentyTwenty--percent of which are +11 DTC (200 stones).percent of which are +11 DTC (200 stones).
Two hundred stones for classifying into:Two hundred stones for classifying into:
Diamond Valuation Class MatrixDiamond Valuation Class MatrixDiamond Valuation Class MatrixDiamond Valuation Class MatrixDiamond Valuation Class MatrixDiamond Valuation Class MatrixDiamond Valuation Class MatrixDiamond Valuation Class MatrixMCC
Complex spreadsheets are required to calculate Complex spreadsheets are required to calculate an average carat price for a parcel.an average carat price for a parcel.
Diamond valuators rely on a Diamond valuators rely on a Diamond valuators rely on a Diamond valuators rely on a
combination of combination of combination of combination of scientific principles (statistics),scientific principles (statistics),scientific principles (statistics),scientific principles (statistics),
historically unique features of historically unique features of historically unique features of historically unique features of
their discipline (DTCtheir discipline (DTCtheir discipline (DTCtheir discipline (DTC----GRGRGRGR----CT),CT),CT),CT),
and and and and ‘‘‘‘field experiencefield experiencefield experiencefield experience’’’’ (price book)(price book)(price book)(price book)
to determine the value of a single to determine the value of a single to determine the value of a single to determine the value of a single stone, or a parcel of stones. stone, or a parcel of stones. stone, or a parcel of stones. stone, or a parcel of stones.
Diamond valuators rely on a Diamond valuators rely on a Diamond valuators rely on a Diamond valuators rely on a
combination of combination of combination of combination of scientific principles (statistics),scientific principles (statistics),scientific principles (statistics),scientific principles (statistics),
historically unique features of historically unique features of historically unique features of historically unique features of
their discipline (DTCtheir discipline (DTCtheir discipline (DTCtheir discipline (DTC----GRGRGRGR----CT),CT),CT),CT),
and and and and ‘‘‘‘field experiencefield experiencefield experiencefield experience’’’’ (price book)(price book)(price book)(price book)
to determine the value of a single to determine the value of a single to determine the value of a single to determine the value of a single stone, or a parcel of stones. stone, or a parcel of stones. stone, or a parcel of stones. stone, or a parcel of stones.