What is a mineral? Naturally occurring Naturally occurring Solid substance Solid substance Orderly crystalline structure Orderly crystalline structure

What is a mineral?What is a mineral?

Naturally occurringNaturally occurring Solid substanceSolid substance Orderly crystalline structureOrderly crystalline structure Definite chemical compositionDefinite chemical composition Generally INORGANICGenerally INORGANIC

Some animals secrete inorganic compounds Some animals secrete inorganic compounds (Calcium carbonate found in shells and coral (Calcium carbonate found in shells and coral reefs)reefs)

Characteristics of MineralsCharacteristics of Minerals

More than 4000 minerals More than 4000 minerals identified, but only 20 are identified, but only 20 are commonly foundcommonly found

Those 20 are known as Those 20 are known as rock-forming minerals, form rock-forming minerals, form the rocks of Earth’s crustthe rocks of Earth’s crust

Of the 20 most common, Of the 20 most common, half of them make up 90% half of them make up 90% of the mass of Earth’s crustof the mass of Earth’s crust

Groups of MineralsGroups of Minerals

Minerals are classified by the Minerals are classified by the elements they are made of.elements they are made of.

Amethyst

Beryl (Emerald) Calcite

Mineral GroupMineral Group CharacteristicsCharacteristics ExamplesExamples

SilicatesSilicates

Contain Contain oxygenoxygen & & silicasilicaThe most The most abundantabundant group of group of mineralsminerals (95%)(95%)

Quartz, micaQuartz, mica

MICA Quartz


Non-SilicatesNon-Silicates

Make up only Make up only 5%5% of the of the Earth’s crustEarth’s crustInclude some Include some of the most of the most important important mineralsminerals

iron, copper, iron, copper, gold, silver, gold, silver, diamonds, diamonds, rubiesrubies

Silver

GoldRuby Iron

Copper

Diamond


CarbonatesCarbonates Carbon & Carbon & oxygen and oxygen and a positive a positive ion, such as ion, such as calciumcalcium

Calcite Calcite (CaCO(CaCO33))

Calcite with Duftite inclusions


OxidesOxides Metallic ion Metallic ion and oxygenand oxygen

Hematite Hematite (Fe(Fe22)O)O33


SulfidesSulfides Sulfur and a Sulfur and a metallic ionmetallic ion

Galena (PbS)Galena (PbS)


SulfatesSulfates Metallic ion, Metallic ion, Sulfur & Sulfur & oxygenoxygen

Barite Barite (BaSO(BaSO44))

Barite on Calcite BaSo4 / CaCO3

BariteBaSo4


Native Native ElementsElements

Single Single elementselements

Gold (Au), Gold (Au), Diamond (C), Diamond (C), Silver (Ag)Silver (Ag)

http://www.gc.maricopa.edu/earthsci/imagearchive/gold.jpg

Chemical Formulas to KnowChemical Formulas to Know Gold - AuGold - Au Silver - AgSilver - Ag Copper - CuCopper - Cu Sulfur - SSulfur - S Diamond - CDiamond - C Graphite - C Platinum Graphite - C Platinum

- Pt- Pt Quartz - SiOQuartz - SiO22

Olivine - (Mg, Fe)Olivine - (Mg, Fe)22SiOSiO44

Hematite - FeHematite - Fe22OO33

Magnetite - FeMagnetite - Fe33OO44

Corundum - AlCorundum - Al22OO33

Galena - PbSGalena - PbS Sphalerite - ZnSSphalerite - ZnS Pyrite - FeSPyrite - FeS22

Halite - NaClHalite - NaCl Fluorite - CaFFluorite - CaF22

Calcite - CaCOCalcite - CaCO33

Crystal StructureCrystal Structure All minerals have a All minerals have a

crystalline structurecrystalline structure A A crystal crystal is a solid is a solid

whose atoms, ions, or whose atoms, ions, or molecules are molecules are arranged in a regular, arranged in a regular, repeating patternrepeating pattern Each type of mineral Each type of mineral

crystal is defined by a crystal is defined by a specific geometric specific geometric arrangement of atomsarrangement of atoms

Physical Properties of Physical Properties of MineralsMinerals

ColorColor LusterLuster StreakStreak Hardness Hardness CleavageCleavage FractureFracture

Crystal SystemCrystal System DensityDensity Special Special

PropertiesProperties

Physical Properties of MineralsPhysical Properties of Minerals (can be used to identify the mineral)(can be used to identify the mineral)

ColorColor Can be Can be misleadingmisleading

For example, Quartz comes in a variety For example, Quartz comes in a variety of colorsof colors

Can vary with the type of impuritiesCan vary with the type of impurities


LusterLuster Surface Surface reflectionreflection metallic = shiny metallic = shiny

like metallike metal non-metallic = non-metallic =

dull, non-shiny dull, non-shiny surfacesurface

Pyrite has a metallic luster

Calcite has a non-metallic luster

Non-metallic LusterNon-metallic Luster

Non-Metallic lusters include:Non-Metallic lusters include: Vitreous (glassy) Vitreous (glassy) Pearly (pearl-like)Pearly (pearl-like) Silky (fiber-like)Silky (fiber-like) Earthy (dull)Earthy (dull)

Non-metallic luster Non-metallic luster Continued.Continued.

Non-metallic lusters include:Non-metallic lusters include: Waxy (greasy appearance)Waxy (greasy appearance) Adamantine (diamond-like)Adamantine (diamond-like) Resinous (plastic-looking)Resinous (plastic-looking)


StreakStreak The The colorcolor of the powdered of the powdered

form of the mineralform of the mineral The color of the streak can The color of the streak can

be different than the mineralbe different than the mineral Minerals must be Minerals must be softersofter than than

the streak platethe streak plate

Streak…can help identify Streak…can help identify quartzquartz

Can oil and natural gas be Can oil and natural gas be classified as minerals? Why classified as minerals? Why

or why not?or why not? Answer: Oil and natural gas cannot Answer: Oil and natural gas cannot

be classified as minerals, because be classified as minerals, because they are not solids, do not form they are not solids, do not form crystals, and do not have a definite crystals, and do not have a definite chemical make-upchemical make-up


Cleavage & FractureCleavage & Fracture The way the mineral The way the mineral breaksbreaks CleavageCleavage—minerals break —minerals break

along along smoothsmooth, flat surfaces , flat surfaces and every fragment has the and every fragment has the same general shapesame general shape

FractureFracture—minerals that —minerals that break at break at randomrandom with rough with rough or jagged edgesor jagged edges

Types of CleavageTypes of Cleavage Basal - 1 planeBasal - 1 plane Prismatic - 2 Prismatic - 2

planesplanes Cubic - 3 planes Cubic - 3 planes

@ 90@ 90 Rhombohedral - 3 Rhombohedral - 3

planes not @ 90planes not @ 90 Octahedral - 4 Octahedral - 4

planesplanes Dodecahedral - 6 Dodecahedral - 6

planesplanes

Types of FractureTypes of Fracture Conchoidal – curvedConchoidal – curved Irregular – unevenIrregular – uneven Fibrous – splinteryFibrous – splintery Hackly – jagged-Hackly – jagged-

edgededged


HardnessHardness How easily a mineral How easily a mineral scratchesscratches

materialsmaterials Mohs Hardness ScaleMohs Hardness Scale

Scale from 1 (Scale from 1 (softestsoftest) to 10 () to 10 (hardesthardest)) Test by seeing if the mineral can scratch Test by seeing if the mineral can scratch

different objects (like human fingernail, different objects (like human fingernail, copper, penny, glass, steel file)copper, penny, glass, steel file)

2.5, 3.5, 5.5, 6.52.5, 3.5, 5.5, 6.5

Crystal SystemCrystal System Crystal form is the visible expression of a Crystal form is the visible expression of a

mineral’s internal arrangement of atomsmineral’s internal arrangement of atoms Every mineral has a crystal formEvery mineral has a crystal form

DensityDensity

Special PropertiesSpecial Properties Magnetism Magnetism Attraction to Attraction to magnets magnets Smell & tasteSmell & taste Fluorescence Fluorescence glows under UV light glows under UV light Phosphorescence Phosphorescence glows after UV glows after UV

light is off (stores light energy light is off (stores light energy longer)longer)

Special PropertiesSpecial Properties Effervescence Effervescence fizzing (HCl on fizzing (HCl on

calcite)calcite) Chatoyancy Chatoyancy silky band when light silky band when light

shined on mineralshined on mineral Asterism Asterism six-sided star appears six-sided star appears

when lightwhen light

Special PropertiesSpecial Properties Double refraction – Double refraction –

light is bent, causing light is bent, causing image to be doubledimage to be doubled Ex. CalciteEx. Calcite

Radioactivity Radioactivity Geiger counterGeiger counter

Describe what would Describe what would happen if you rubbed a happen if you rubbed a

mineral with a Mohs mineral with a Mohs hardness value of 7 against hardness value of 7 against a mineral with a value of 5.a mineral with a value of 5.

The one with a hardness of 5 would The one with a hardness of 5 would be scratched, because the mineral be scratched, because the mineral with a hardness of 7 is harder.with a hardness of 7 is harder.

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What is a mineral? Naturally occurring Naturally occurring Solid substance Solid substance Orderly crystalline structure Orderly crystalline structure