Minerals

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L3 - MINERALS

CIVE 430 ENGINEERING GEOLOGY

SUMMER 2013

DEFINITION Theearth,theotherinnerplanetsandthemoonare

madeofROCKS. Rocksinturn,aremadeofMINERALS

MINERALSare: Solids;naturalcompoundsANDtheyhave AregularstructuremadeofATOMSheldtogetherby

electromagneticforces Afixedchemicalcomposition.

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WhatisaMineral?

PeriodicTable http://www.webelements.com/

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MineralClassificationMineralsofonetypeofatom nativeelements(Augold,Ag silver,Cu copper,)

MineralswithCationscombinedwiththelarge,negativeions(anions): oxygen(O oxides),sulfur(S sulfides),halogens(Cl,ForBr halides).

Aniongroupsmadeofoxygen combinedwithcationsofvalency+3orgreater(seeperiodictablenonmetalsofgroups1317):silicates(SiO4),carbonates(CO3)andsulfates(SO4).

MineralStructureThisarrangement,knownasCrystalStructure isdeterminedby: Theatomsize TheTypesofBonds:ionic,covalent,VanderWaals

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Howaremineral'sformedinnature? Fromawatersolution.Thechemicalsinthesolutioncome

fromdissolvingotherminerals.Thesemineralsformatthesurfaceoftheearthaswaterevaporates(sedimentary)orfromhotwaterinsidetheearthasthatwatercools(hydrothermal).

Fromasilicatemelt. Themeltcomesfrommeltingminerals.Thesemineralsform:Wheremoltenrockcools eitherintheinteriororatthesurface(igneous).

Byaddingenergytominerals,rearrangetheionsoftheoldstructureandmakeanewone.

ThesemineralsformInsidetheearthwherehightemperaturesprovidethenecessaryenergy(metamorphic).

PHYSICALCHARACTERISTICSOFMINERALS

Color Luster Cleavage Fracture Hardness SpecificGravity Streak

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PHYSICALCHARACTERISTICSOFMINERALS

COLOR: Cobalt,Co,produces: violetred Chromium,Cr,produces: orangered Copper,Cu,produces: azureblue Iron,Fe,produces: red Manganese,Mn,produces: pink Nickel,Ni,produces: green Uranium,U,produces: yellow Vanadium,V,produces: Redorange

PHYSICALCHARACTERISTICSOFMINERALSSTREAK: Colorofthemineralmaybe

differentthanthecolorofthestreak.Streakisactuallythecolorofthepowderofamineral

Properwaytotestforstreakistorubamineralacrossatileofwhiteporcelainandtoexaminethecolorofthe"streak"leftbehind

HEMATITE

StreakisBloodRED

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PHYSICALCHARACTERISTICSOFMINERALSSTREAK

HEMATITE

Streak is Blood RED

PHYSICALCHARACTERISTICSOFMINERALSLUSTER

Descriptionofthewaylightinteractswiththesurfaceofacrystal.Ithasnothingtodowithcolororshape,butisrelatedtotransparencyandsurfaceconditions.

Dull justanonreflectivesurfaceofanykind Earthy thelookofdirtordriedmud Fibrous thelookoffibers Greasy thelookofgrease Metallic thelookofmetals Pearly thelookofapearl Pitchy thelookoftar Resinous thelookofresinssuchasdriedglueorchewinggum Vitreous simplymeansthelookofglass Waxy thelookofwax

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PHYSICALCHARACTERISTICSOFMINERALSLUSTER FibrousAsbestos

CLEAVAGE Crystalcleavageisasmoothbreakproducingwhatappearstobeaflatcrystalface

cleavageisreproducible thesamemineralwillalwayshavethesamecleavage.

CALCITECleavageisperfectin3directions,formingrhombohedrons

PHYSICALCHARACTERISTICSOFMINERALS

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Cleavage.GemsSalt

PHYSICALCHARACTERISTICSOFMINERALS

NoCleavageConcoidalFractureOBSIDIAN

Salt

FRACTURE

PHYSICALCHARACTERISTICSOFMINERALS

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HARDNESS Hardnessisameasureofthestrength

ofthestructureofthemineralrelativetothestrengthofitschemicalbonds

Hardnesscanbetestedthroughscratching.Groovesrequireeitherthebreakingofbondsorthedisplacementofatoms. Ahardmineralcanscratchasoftermineral,butasoftmineralcannotscratchahardermineral.

TheMohs HardnessScale DiamondMhoHardness=10

PHYSICALCHARACTERISTICSOFMINERALS

MhosHardnessScale1. Talc2. Gypsum3. Calcite4. Fluorite5. Apatite6. Orthoclase7. Quartz8. Topaz9. Corundum(rubyandsapphire)10.Diamond

PHYSICALCHARACTERISTICSOFMINERALS

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Mhos Scale

MhosScale

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DiamondStructure

Diamond Structure

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DENSITY SPECIFICGRAVITY Gold caneasilybedistinguishedfrom

"fool'sgold" byspecificgravityalone SGorGs =Densityofthemineral

dividedbythedensityofwater TheEarth'scrust,wherewearemost

likelytocollectmineralsfrom,iscomposedmostlyofthemineralsquartz,calcite andfeldspar. ThesemineralshaveSG'saround2.7

PHYSICALCHARACTERISTICSOFMINERALS

Rock Forming MineralsOxides (containing O2-)-SAPPHIRE (Corundum)

Sulfides (containing S2-)-GALENA

Sulfates (containing SO42-)-GYPSUM

Native Elements-SILVER

Halides (salts)-FLUORITE

Carbonates (containing CO32-)-CALCITE

Hydroxides (containing OH-)-MANGANITE

Phosphates (containing PO43-)-FLUORAPATITE

SILICATES (containing SiO44-)

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Rock Forming Minerals

RockFormingMineralsCarbonates

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Rock Forming MineralsCarbonates

Rock Forming MineralsSilicate MineralsForm 95% of the Earth's crust

>80% of the Earth's mantle

Why?

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RockFormingMineralsSilicateMinerals Quartz Feldspars(Orthoclase,Plagioclase) Mica(Muscovite,Biotite) Clay(Kaolinite,Montmorillonite) OlivineAmphibolePyroxine (Groups) Garnet Serpentine

RockFormingMineralsSilicateStructure

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RockFormingMineralsSheetStructure Mica

RockFormingMineralsSilicateMinerals

Feldspar Mica

PyroxeneQuartzOlivine

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RockFormingMineralsNonSilicateMinerals

Halite Spinel

CalcitePyriteGalena

Gypsum

Hematite