MineralsMinerals

Objective: Minerals

• To learn the definition of a mineral• To understand what an ore is• To learn the different physical

properties of minerals

Quickwrite: Answer one of the questions below in 1-2 sentences

• What are some minerals that we use in our everyday lives?

• What is the name of the mineral we use in our pencils?

• How do you think we tell minerals apart?

Rocks:Rocks:A mixture A mixture of mineralsof minerals

MineralsMinerals• To determine whether a substance is a To determine whether a substance is a

mineral or non-mineral, scientists ask four mineral or non-mineral, scientists ask four basic questions basic questions

• First, is it inorganic? (Not made of living First, is it inorganic? (Not made of living things such as coal) things such as coal)

• Second, did the substance form naturally? Second, did the substance form naturally? (not manmade such as steel which is a (not manmade such as steel which is a combination of metals) combination of metals)

• Third, is the substance a solid or crystalline Third, is the substance a solid or crystalline form? (Such as the quartz up in the corner form? (Such as the quartz up in the corner of this slide)of this slide)

• Finally, does the substance have a Finally, does the substance have a consistent chemical composition?consistent chemical composition?

Is it a Mineral or Not?Coal Steel Granite Halite

Is it inorganic? No Yes Yes Yes

Does it occur naturally?

No Yes Yes

Is it a crystalline solid?

No Yes

Does it have a consistent chemical composition?(is it pure?)

Yes

Mineral or not?Mineral or not?

• A mineral is a natural, inorganic solid A mineral is a natural, inorganic solid with a definite chemical structure and with a definite chemical structure and compositioncomposition

So What is a Mineral?So What is a Mineral?

• A mineral is a natural, _____ solid with a A mineral is a natural, _____ solid with a definite chemical structure and definite chemical structure and compositioncomposition

Answer BankreflectsProfit

InorganicFlat

crystal

OresOres

• An ore is a mineral deposit that we An ore is a mineral deposit that we remove form the earth for profitremove form the earth for profit($$$($$$$)$)Bingham mineBingham mine

Utah USAUtah USA

Worlds largest Worlds largest

MineMine

Examples of Some OresExamples of Some Ores• Bauxite for aluminiumBauxite for aluminium• Hematite for iron Hematite for iron • Malachite and azurite Malachite and azurite

for copperfor copper• Sphalerite for zincSphalerite for zinc• Cinnabar for MercuryCinnabar for Mercury• Galena is the ore for LeadGalena is the ore for Lead

What is an Ore?What is an Ore?

• An ore is a mineral deposit that we An ore is a mineral deposit that we remove form the earth for _____remove form the earth for _____($$$($$$$)$)

Answer BankreflectsProfit

InorganicFlat

crystal

Physical Properties• In order to identify minerals, geologists use

a minerals physical properties to help identify them

• Many minerals look the same and are hard to tell apart

• In order to identify them, geologists use the following physical properties to identify them:– HardnessHardness– LusterLuster– ColorColor– StreakStreak– Crystal Shape or FormCrystal Shape or Form– CleavageCleavage– Special PropertiesSpecial Properties

Appearance• Never use appearance to tell

minerals apart• Why? Because many mineral

look very similar if not identical to each other

• For example, how can we tell pyrite (fool’s gold) apart from real gold?

• Or, how can we tell gold apart from copper?

• Which one is gold?• Which one is copper?• Which one is pyrite?

Which One Is It?Which One Is It?

Physical Properties:Physical Properties: Hardness Hardness

• One way we classify minerals is One way we classify minerals is hardnesshardness• A measure of how easily a mineral can be A measure of how easily a mineral can be

scratched is its hardnessscratched is its hardness• The mineral talc for example, can be The mineral talc for example, can be

scratched with a fingernailscratched with a fingernail• Talc is so soft, we make baby powder out of Talc is so soft, we make baby powder out of

itit• On the other hand, diamonds, are the On the other hand, diamonds, are the

hardest substance know to manhardest substance know to man• A diamond can only be scratched by A diamond can only be scratched by

another diamond another diamond

Moh’s Hardness ScaleMoh’s Hardness Scale• A mineral hardness A mineral hardness

scale (1-10) was scale (1-10) was developed by Friedrich developed by Friedrich Mohs Mohs

• Mohs hardness scale has Mohs hardness scale has talc being the softest talc being the softest (1), and diamonds being (1), and diamonds being the hardest (10) the hardest (10)

• This scale is used to This scale is used to help us identify help us identify unknown mineralsunknown minerals

• Harder minerals can Harder minerals can scratch softer mineralsscratch softer minerals

• Can Topaz scratch Can Topaz scratch fluorite?fluorite?

Diamond vs. GraphiteDiamond vs. GraphiteWhy is graphite soft and diamond so Why is graphite soft and diamond so

hard?hard?

• Graphite and diamond are Graphite and diamond are both made up of pure both made up of pure CarbonCarbon

• But why is one soft and But why is one soft and used to write with, and used to write with, and the other is very precious?the other is very precious?

• The answer is in the The answer is in the internal structure of the internal structure of the mineralmineral

• The chemical bonds in The chemical bonds in diamonds are very strong diamonds are very strong and rigid compared to the and rigid compared to the chemical bonds in chemical bonds in graphitegraphite

Physical Properties:Physical Properties: Luster Luster

• Another way we classify minerals is LusterAnother way we classify minerals is Luster• Luster is how light is reflected from a minerals Luster is how light is reflected from a minerals

surfacesurface

• Many minerals have a metallic luster

• Others have a vitreous or glassy Luster

• Some may have a dull or pearly Luster

Physical Properties:Physical Properties: StreakStreak

• Another way we classify Another way we classify minerals is by minerals is by streakstreak

• Streak is theStreak is the color of the color of the mineral when it is broken up mineral when it is broken up or in powdered formor in powdered form

• When a mineral is rubbed When a mineral is rubbed against a Porcelain plate, a against a Porcelain plate, a streak is left behindstreak is left behind

• This streak is the powdered This streak is the powdered mineral mineral

• Remember gold and pyrite?Remember gold and pyrite?• Gold has a yellow streak and Gold has a yellow streak and

pyrite has a black streakpyrite has a black streak• Hematite leaves a red streakHematite leaves a red streak

Physical Properties:Physical Properties: Cleavage & Cleavage & FractureFracture

• The way a mineral breaks is The way a mineral breaks is another clue to it’s identityanother clue to it’s identity

• Minerals that break along Minerals that break along smooth, flat mineral surfaces smooth, flat mineral surfaces have cleavagehave cleavage

• Cleavage, like hardness, is Cleavage, like hardness, is determined by the determined by the arrangement of the minerals arrangement of the minerals atomsatoms

• Mica is a mineral that has Mica is a mineral that has perfect cleavageperfect cleavage

• Not all minerals have cleavageNot all minerals have cleavage• Minerals that break rough and Minerals that break rough and

uneven have fractureuneven have fracture (example: Quartz)(example: Quartz)

Physical Properties:Physical Properties: ColorColor• Another obvious way we tell Another obvious way we tell

minerals apart is by there minerals apart is by there colorcolor

• However, color can be However, color can be deceptive and is not an deceptive and is not an accurate way to identify a accurate way to identify a mineral!!!!!!!!!!!!!!!!!!mineral!!!!!!!!!!!!!!!!!!

• Some minerals like sulfur are Some minerals like sulfur are always yellow and never always yellow and never change colorchange color

• Most minerals like quartz can Most minerals like quartz can be many different colors be many different colors

• Impurities can cause minerals Impurities can cause minerals to have many different colorsto have many different colors

Physical Properties:Physical Properties: Crystal Crystal FormForm

• Another Way we identify minerals is Another Way we identify minerals is by there crystal shape or formby there crystal shape or form

• Minerals, as we know, can form into Minerals, as we know, can form into various geometric shapesvarious geometric shapes

• These crystal shapes are the result of These crystal shapes are the result of the minerals internal chemistry and the minerals internal chemistry and how they formhow they form

• Each Mineral has it’s own unique Each Mineral has it’s own unique crystal shape crystal shape

HexagonalHexagonalExamples: Quartz, CorundumExamples: Quartz, Corundum

RhombohedralRhombohedralExample: CalciteExample: Calcite

OctahedralOctahedralExample: Flourite, DiamondExample: Flourite, Diamond

DodecahedralDodecahedralExample: GarnetExample: Garnet

CubicCubicExample: Pyrite, HaliteExample: Pyrite, Halite

Physical Properties:Physical Properties: Special Properties

• Some minerals have Some minerals have Special Special PropertiesProperties that make them easy to that make them easy to identifyidentify

• Magnetite, as you might have Magnetite, as you might have guessed, is guessed, is magneticmagnetic Magnetite is attracted to other Magnetite is attracted to other

magnets and will change the magnets and will change the compass needle directioncompass needle direction

• Calcite has Calcite has double refractiondouble refraction When light passes through calcite, When light passes through calcite,

it breaks light up into two it breaks light up into two directions creating a double imagedirections creating a double image

• Besides a bright yellow colorBesides a bright yellow color, Sulfur , Sulfur has an unpleasant odor, has an unpleasant odor, making it making it easy to identifyeasy to identify

• Halite (salt) has a taste Halite (salt) has a taste to it that also to it that also makes it easy to identifymakes it easy to identify

Fluorescent Minerals

• Fluorescence is a special property where minerals glow or give off light under Ultra violet light

What are a mineral’s physical What are a mineral’s physical properties?properties?

– Hardness: a measure of easily a mineral can be scratched

– Luster: how a mineral ____ light ex. Metallic or vitreous

– Color– Streak: a mineral’s color in powdered form

when rubbed on a porcelain plate– Crystal Shape or Form: characteristic ____shape– Cleavage: tendency of a mineral to break along

____ planes– Fracture: mineral that break unevenly or

irregular– Special Properties: odor, taste, magnetism

Answer BankreflectsProfit

InorganicFlat

geometric

SummarizeSummarize

– A mineral is a natural, ______ solid A mineral is a natural, ______ solid with a definite chemical structure and with a definite chemical structure and compositioncomposition

– We tell minerals apart by their We tell minerals apart by their physical _____physical _____

– Minerals that break along flat Minerals that break along flat surfaces is called ________surfaces is called ________

– Magnetite is a mineral that is ________Magnetite is a mineral that is ________

Answer Bankreflects

magneticInorganicpropertiescleavage