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MineralsMinerals
MineralsMinerals
Natural, usually inorganic solid that has a Natural, usually inorganic solid that has a characteristic chemical composition, an characteristic chemical composition, an orderly internal structure, and a orderly internal structure, and a characteristic set of physical properties.characteristic set of physical properties.
Is it a Mineral?Is it a Mineral?
Is it organic?Is it organic? Does it occur naturally?Does it occur naturally? Is it a crystalline solid?Is it a crystalline solid? Consistent chemical composition?Consistent chemical composition? Must answer yes to all 4 questions for it to Must answer yes to all 4 questions for it to
be a mineralbe a mineral
10 Most common minerals10 Most common minerals
QuartzQuartz CalciteCalcite OrthoclaseOrthoclase DolomiteDolomite PlagioclasePlagioclase HaliteHalite MuscoviteMuscovite GypsumGypsum BiotiteBiotite FerromagnesianFerromagnesian CalciteCalcite MineralsMinerals These make up 90% of Earth’s massThese make up 90% of Earth’s mass
Mineral GroupsMineral Groups
SilicatesSilicates– 96% of Earth’s crust96% of Earth’s crust– Contains Si and OContains Si and O– Can have other elements alsoCan have other elements also– Feldspar – Orthoclase if K, Plagioclase if Na or Feldspar – Orthoclase if K, Plagioclase if Na or
CaCa– Ferromagnesian minerals – rich in FeFerromagnesian minerals – rich in Fe
Mineral GroupsMineral Groups
Nonsilicate MineralsNonsilicate Minerals– Do not contain Si and ODo not contain Si and O
Can contain one or the other, but not bothCan contain one or the other, but not both
– Six groupsSix groups CarbonatesCarbonates Native elementsNative elements HalidesHalides OxidesOxides SulfatesSulfates SulfidesSulfides
Crystalline StructureCrystalline Structure
Crystal – atoms, ions, or molecules are Crystal – atoms, ions, or molecules are arranged in a regular, repeating patternarranged in a regular, repeating pattern
Silicate crystal structureSilicate crystal structure– Silicon – oxygen tetrahedronSilicon – oxygen tetrahedron– 1 Si with 4 O’s around it1 Si with 4 O’s around it– Basic building block of silicatesBasic building block of silicates– Can be connected 6 different waysCan be connected 6 different ways
Crystalline StructureCrystalline Structure
Nonsilicate crystalsNonsilicate crystals– Diverse chemical composition leads to variety of Diverse chemical composition leads to variety of
crystal structurescrystal structures– Cubes, hexagonal prisms…Cubes, hexagonal prisms…– Crystal structure influences physical propertiesCrystal structure influences physical properties
Native elements are dense due to compact crystal Native elements are dense due to compact crystal structurestructure
Silicate TetrahedronSilicate Tetrahedron
Physical PropertiesPhysical Propertiesof Mineralsof Minerals
MineralogistMineralogist– Examine, analyze, and classify mineralsExamine, analyze, and classify minerals
Result from chemical composition and Result from chemical composition and crystal structurecrystal structure
Can be useful in identifying mineralsCan be useful in identifying minerals
Physical PropertiesPhysical Properties
1)1) ColorColor• Not reliable for ID purposesNot reliable for ID purposes• Small amount of impurities can affect colorSmall amount of impurities can affect color• Weathered surfaces may hide colorWeathered surfaces may hide color• Only look at fresh surfacesOnly look at fresh surfaces
ColorColor
Physical PropertiesPhysical Properties
2)2) StreakStreak• Color of mineral in powder formColor of mineral in powder form• Streak plate – unglazed ceramic tileStreak plate – unglazed ceramic tile• Streak color may differ from mineral colorStreak color may differ from mineral color• Metallic minerals – darker streakMetallic minerals – darker streak• Nonmetallic minerals – lighter streakNonmetallic minerals – lighter streak
StreakStreak
Physical PropertiesPhysical Properties
3)3) LusterLuster Light reflected from mineral’s surfaceLight reflected from mineral’s surface Metallic luster – shiny surfaceMetallic luster – shiny surface Nonmetallic lusterNonmetallic luster
GlassyGlassy WaxyWaxy PearlyPearly BrilliantBrilliant Dull / EarthyDull / Earthy
Metallic LusterMetallic Luster
Glassy LusterGlassy LusterQuartzQuartz
Waxy LusterWaxy LusterVarisciteVariscite
Pearly LusterPearly LusterTalcTalc
Brilliant LusterBrilliant LusterDiamondDiamond
Dull / Earthy LusterDull / Earthy LusterPsilomelanePsilomelane
Physical PropertiesPhysical Properties
4)4) Cleavage / FractureCleavage / Fracture– CleavageCleavage
splitting along specific lines of weaknesssplitting along specific lines of weakness Forms smooth, flat surfacesForms smooth, flat surfaces
– FractureFracture Break unevenly into piecesBreak unevenly into pieces Forms curved, irregular surfacesForms curved, irregular surfaces Conchoidal fractures – curved surfaceConchoidal fractures – curved surface
Cleavage - CalciteCleavage - Calcite
FractureFractureConchoidalConchoidal
FractureFractureIrregularIrregular
Physical PropertiesPhysical Properties
5)5) HardnessHardness Ability to resist scratchingAbility to resist scratching Mohs Hardness ScaleMohs Hardness Scale
Scale of 1 to 10Scale of 1 to 10 1 = Talc1 = Talc 10 = Diamond10 = Diamond Glass is about a 5Glass is about a 5
Mohs Hardness ScaleMohs Hardness Scale
Physical PropertiesPhysical Properties
6)6) Crystal ShapeCrystal Shape– 6 Basic shapes6 Basic shapes– Certain minerals always form crystals with the Certain minerals always form crystals with the
same shapesame shape
7)7) DensityDensity– Ratio of mass to volumeRatio of mass to volume– Can help identify mineralsCan help identify minerals
Crystal ShapesCrystal Shapes
Physical PropertiesPhysical Properties
Fluorescence and phosphorescenceFluorescence and phosphorescence Chatoyancy and asterismChatoyancy and asterism Double refractionDouble refraction MagnetismMagnetism RadioactivityRadioactivity
Double RefractionDouble Refraction