Minerals. Minerals Natural, usually inorganic solid that has a characteristic chemical composition, an orderly internal structure, and a characteristic.

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