Rocks and Minerals

I. Rocks vs Minerals

A.A. Rock – Rock – solid part of earth, make up solid part of earth, make up lithospherelithosphere

B.B. ALL rocks are made of ALL rocks are made of mineralsminerals

1.1. MonomineralicMonomineralic – rocks made up of – rocks made up of only only ONEONE mineral mineral

2.2. PolymineralicPolymineralic – rocks made of – rocks made of severalseveral (3 or more) minerals(3 or more) minerals

II. Definition of a Mineral

A.A. NaturallyNaturally occurringoccurringB.B. SolidSolid at normal earth surface at normal earth surface temperaturestemperaturesC.C. AtomsAtoms are arranged in an are arranged in an orderlyorderly, ,

repetitive pattern (repetitive pattern (crystalscrystals))D.D. Made of Made of 22 or more or more elementselementsE.E. Generally considered Generally considered inorganicinorganic (not from (not from

living things, exception = living things, exception = calcitecalcite in in seashells)seashells)

III. Silicates

A.A. Most Most commoncommon group of group of mineralsminerals

B.B. Made up of Made up of oxygenoxygen and and siliconsilicon

C.C. Silicon-Oxygen Silicon-Oxygen TetrahedronTetrahedron – basic unit – basic unit of structure of of structure of ALLALL silicatessilicates

III. Silicates (cont)

D.D. Most common elements in Most common elements in lithospherelithosphere

1.1. By volume = By volume = OxygenOxygen 94%94%

2.2. By mass = Oxygen By mass = Oxygen 4646%, Silicon %, Silicon 2828%%

III. Silicates (cont)

E.E. Physical properties of Physical properties of minerals are minerals are determined determined by the by the arrangement of the arrangement of the atoms atoms

IV. Mineral Identification

A.A. ColorColor – – NOTNOT very useful since most very useful since most minerals can be found in minerals can be found in MANYMANY different different colorscolors

IV. Mineral Identification (cont)

B.B. LusterLuster – way it shines– way it shines

1.1. MetallicMetallic – shines like metal– shines like metal

2.2. Non-metallicNon-metallic – dull, pearly, earthy – dull, pearly, earthy

IV. Mineral Identification (cont)

C.C. StreakStreak – color of – color of powderedpowdered mineralmineral

1.1. ScratchScratch on streak plate and note on streak plate and note colorcolor

2.2. Some have Some have NONO streak if very streak if very hardhard

IV. Mineral Identification (cont)

D.D. HardnessHardness – depends on – depends on arrangementarrangement of of atomsatoms

1.1. GraphiteGraphite = = 1 1

2.2. DiamondDiamond = = 10 10

3.3. Both made of Both made of carboncarbon, but arranged , but arranged differentlydifferently

IV. Mineral Identification (cont)

IV. Mineral Identification (cont)

E.E. CleavageCleavage – does it break along – does it break along flatflat surfacessurfaces

1.1. CleavageCleavage – breaks with flat – breaks with flat surfacessurfaces

2.2. FractureFracture – shatters with – shatters with NONO flat surfacesflat surfaces

3.3. Determined by arrangement of atomsDetermined by arrangement of atoms

IV. Mineral Identification (cont)

IV. Mineral Identification (cont)

F.F. DensityDensity = = MassMass / / VolumeVolume

G.G. TasteTaste – Halite tastes – Halite tastes saltysalty (rock salt)(rock salt)

NEVER - EVER TASTE ANYTHING IN SCIENCE CLASS!

F.F. ReactionReaction with HClwith HCl

1.1. Some minerals Some minerals bubblebubble with HCl (with HCl (CalciteCalcite))

IV. Mineral Identification (cont)

V. Igneous Rocks

A.A. Form when Form when moltenmolten (hot, melted) rock (hot, melted) rock solidifiessolidifies as it cools forming crystals as it cools forming crystals ((crystallizationcrystallization))

V. Igneous Rocks (cont)

Magma – molten rock below surface

Extrusive (volcanic) – forms @ surface

-Rapid Cooling

-Small Crystals

-Fine Texture

Lava – molten rock @ surface

V. Igneous Rocks (cont)

B.B. ExtrusiveExtrusive ExamplesExamples

Rhyolite

Basalt

Vesicular Basalt

V. Igneous Rocks (cont)

Intrusive (Plutonic) – forms below surface (inside)

-Slow Cooling

-Large Crystals

-Coarse Texture

V. Igneous Rocks (cont)

C.C. IntrusiveIntrusive ExamplesExamples

Granite

Gabbro

Pegmatite

V. Igneous Rocks (cont)

D.D. Naming Igneous Rocks – based on Naming Igneous Rocks – based on compositioncomposition, , texturetexture, , colorcolor and and densitydensity

V. Igneous Rocks (cont)

VI. Sedimentary Rocks

A.A. Form with the help of Form with the help of waterwater

B.B. TypesTypes

1.1. ClasticClastic – (– (fragmentalfragmental) )

a.a. formed when formed when sedimentssediments are are depositeddeposited and then and then compressedcompressed and and cementedcemented togethertogether

b.b. Found in Found in layerslayers ((stratifiedstratified))

VI. Sedimentary Rocks (cont)

Sandstone

ConglomerateShale

VI. Sedimentary Rocks (cont)2.2. EvaporitesEvaporites ((chemicalchemical))

a.a. Formed when Formed when dissolveddissolved chemical chemical substances form rocksubstances form rock

b.b. As water As water evaporatesevaporates, dissolved , dissolved materials come out of materials come out of solutionsolution

VI. Sedimentary Rocks (cont)

LimestoneDolostone

VI. Sedimentary Rocks (cont)

3.3. OrganicOrganic Sedimentary RocksSedimentary Rocks

a.a. Form either directly or indirectly from Form either directly or indirectly from livingliving thingsthings

b.b. CoalCoal – formed from – formed from treestrees and other and other plantsplants in swampy areas millions of in swampy areas millions of years agoyears ago

c.c. FossiliferousFossiliferous LimestoneLimestone – shells of – shells of animals are animals are cementedcemented togethertogether

VI. Sedimentary Rocks (cont)

Coal

Fossils

Coquina

VII. Sed Rocks Show Past Env

A.A. GrainGrain Size – shows how Size – shows how deepdeep water was water was in area where rocks formedin area where rocks formed

1.1. LargeLarge grains – grains – shallowshallow waterwater

2.2. SmallSmall grains – grains – deepdeep waterwater

3.3. ShaleShale on top of on top of ConglomerateConglomerate = = shallow water followed by deep water shallow water followed by deep water ((bottom rock is olderbottom rock is older))

VII. Sed Rocks Show Past Env

B.B. FossilsFossils

1.1. RemainsRemains, , imprintsimprints or traces of ancient or traces of ancient plantsplants or or animalsanimals

2.2. Found Found ONLYONLY in sedimentary rocksin sedimentary rocks

3.3. Tells the kinds of Tells the kinds of conditionsconditions that were that were there when the sediments were there when the sediments were depositeddeposited

VII. Sed Rocks Show Past Env

Fossilized Ferns

Fossilized Trilobites

Sedimentary Rock ID Chart

VIII. Metamorphic Rocks

A.A. ““ChangedChanged Rocks”Rocks”

B.B. Form from Form from otherother rocks (rocks (sed, ign or metased, ign or meta) ) as a result of as a result of heatheat, , pressurepressure and/or and/or chemical activitychemical activity

C.C. Rocks Rocks recrystallizerecrystallize w/o melting w/o melting

VIII. Metamorphic Rocks

D.D. ClassesClasses

1.1. RegionalRegional – formed by – formed by forcesforces over over LARGELARGE areasareas

a.a. DeepDeep within Earth, high temp and within Earth, high temp and pressure from pressure from mountainmountain buildingbuilding

2.2. ContactContact – formed where – formed where moltenmolten rock rock contactscontacts existingexisting rock rock

a.a. HighHigh temp changes rocktemp changes rock

VIII. Metamorphic Rocks (cont)

VIII. Metamorphic Rocks (cont)

E.E. Changes caused by metamorphismChanges caused by metamorphism

1.1. BandingBanding – minerals concentrated into – minerals concentrated into zones of different zones of different colorscolors ((looks like looks like broken layersbroken layers))

Gneiss

MicaSchist

VIII. Metamorphic Rocks (cont)

2.2. DistortionDistortion – – twistingtwisting of rock structureof rock structure

VIII. Metamorphic Rocks (cont)

3.3. Increased Increased DensityDensity – rock particles are – rock particles are squeezed closer togethersqueezed closer together

4.4. ChemicalChemical Changes – new Changes – new mineralsminerals may formmay form

VIII. Metamorphic Rocks (cont)F.F. Common RocksCommon Rocks

Marble Slate

Gneiss Schist

VIII. Metamorphic Rocks (cont)

A.A. Three types of rocks are Three types of rocks are IgneousIgneous, , SedimentarySedimentary and and MetamorphicMetamorphic

B.B. Rocks are classified based on their Rocks are classified based on their originorigin

C.C. Interactions with Interactions with airair, , waterwater and and landland can can cause rocks to change to a cause rocks to change to a differentdifferent typetype

D.D. This continuous process is the This continuous process is the rock cyclerock cycle

Rock Cycle

IX. Rock Cycle

X. Classifying Rocks

A.A. SedimentarySedimentary – – earthyearthy (dull) and show (dull) and show layerslayers, may contain , may contain fossilsfossils

B.B. IgneousIgneous – – GlassyGlassy and/or contains and/or contains crystalscrystals, , NEVERNEVER has fossils, could have has fossils, could have gas pockets (gas pockets (vesicularvesicular))

C.C. MetamorphicMetamorphic – may show – may show bandingbanding (fake (fake layers) and be layers) and be twistedtwisted or folded, or folded, intergrownintergrown crystalscrystals