MINERALS

Chemical composition of the Crust n Oxygen most abundant- 46.6% n Followed by silicon and aluminum n Iron, Calcium, Sodium, Potassium, Magnesium n The most common minerals will be composed mostly of these elements n Silica & silicates

MINERAL vs. ROCK n ROCK u An aggregate of one or more MINERALS (usually- coal, organic) n MINERAL u Solid u Crystalline- orderly arrangement of atoms u Naturally occurring u Inorganic u Definite chemical composition F e.g. SiO 2 for quartz; KAlSi 3 O 8 for feldspar

Atom & Elements n Atoms u Neutral u Nucleus F Proton, neutron u Electron n Ions u Electrical Charge n Molecule- e.g. water molecule

Chemical activity n Stable atoms want u positive & negative charges balanced u electron shells full n Ions- positive (Cations) and negative (Anions) n Bonding u Ionic u Covalent u Metallic u Van der Waal’s

Element n Atomic number u Number of PROTONS n Isotope u Differing number of NEUTRONS n Atomic weight u Mass of PROTONS and NEUTRONS

Crystallinity n 3 dimensional orderliness of atoms n Silicon-oxygen tetrahedron n Silicate structures u Single- e.g. olivine u Chain F Single chain- pyroxene F Double chain- amphibole u Sheet- e.g. mica, clay u Framework- e.g. quartz, feldspar

MINERALS n Crystalline solids n Natural and Inorganic Substances n Definite chemical composition u Can be written as a chemical formula u Solid solution (within a range)

Important Minerals n Quartz (most abundant) n FELDSPAR Group u Potassium Feldspar - Orthoclase u Plagioclase Feldspar F Sodium (Na) Albite F Calcium (Ca) Anorthosite

Important Minerals n PYROXENE Group- Augite most common n AMPHIBOLE Group- Hornblende most common n MICA Group- Si + O in sheets u Biotite u Muscovite n CALCITE- CaCO 3

Properties of Minerals n Color u Not always reliable (Olivine, green; Flourite, yellow, purple, green…) u Ferromagnesian minerals green or black n Streak- powdered form n Luster- reflectance of light u Metallic u Nonmetallic F Vitreous or Glassy F Earthy

Properties of Minerals n Hardness- resistance to scratching n Moh’s Hardness Scale u Fingernail = 2.5 u Penny = 3.5 u Knife/Glass = 5.5 u Streak Plate= 6.5

Properties of Minerals n Cleavage u Quality (poor, good, perfect) u Number of directions F One- e.g. Mica F Two at right angles- e.g. Feldspar, Pyroxene F Two not at right angles- e.g. Amphibole F Three at right angles (cubic)- e.g. Halite F Three not at right angles (rhombohedral)- e.g. calcite F Four (Flourite) or six (Sphalerite)- not common

Properties of Minerals n Fracture u Absence of cleavage u Irregular fracture u Conchoidal fracture- Quartz n Density u Specific Gravity n Some unusual properties u Striations, Magnetism, Taste, Odor, Double refraction

Chemical tests n Reaction with HCl u Calcite effervesces

Mineral Groups n Silicates n Carbonates n Oxides n Sulfides n Sulfates n Native Elements n Halides

Silicates n Quartz n Feldspar u Plagioclase u Orthoclase n Micas u Muscovite u Biotite n Amphibole (Hornblende) n Pyroxene (Augite) n Olivine

Carbonates n Calcite (calcium carbonate) n Dolomite (calcium-magnesium carbonate) n Both are used as Portland Cement

Oxides n Hematite (iron oxide) u Iron ore, pigment n Magnetite u Iron ore n Corundum (aluminum oxide) u Sapphire, ruby (gemstone) u Abrasive

Sulfides n Galena (Lead sulfide) u Lead ore n Sphalerite Zinc sulfide) u Zinc ore n Pyrite (Iron sulfide) u Sulfuric acid n Chalcopyrite (Copper Iron sulfide) u Copper ore

Sulfates n Gypsum n Anhydrite n Both use in plaster

Native Elements n Gold- trade, instruments n Silver- photography, conductors n Copper- electrical n Platinum- catalysts n Sulfur- chemicals, pharmaceuticals n Diamond- carbon u Gemstone, abrasive n Graphite- carbon u Lubricant, pencils

ROCK CYCLE n Equilibrium n Interrelationships between u igneous rocks u sediment u sedimentary rocks u metamorphic rocks u weathering and erosion

Rocks Classification of Igneous, Sedimentary and Metamorphic Rocks

IGNEOUS ROCKS EXTRUSIVE Volcanic- Fine-grained INTRUSIVE Plutonic- Coarse-grained

MAGMA n Molten Rock u Usually with dissolved gasses n Generated at depth n Eruptions if magma (lava) reaches surface n If doesn’t reach surface, Solidifies underground u Intrudes country or host rock u Intrusive contact u Xenolith- ‘foreign body’

Igneous Rocks n Names based on mineral composition reflects chemical composition of the magma and... Grain size u Very coarse-grained Pegmatitic u Coarse-grained: Phaneritic > 1 mm. u Fine-grained: Aphanitic < 1 mm. u Porphyritic- 2 crystal sizes

Igneous Rocks- Classification n Coarse-grained- n Plutonic (Intrusive) u Granite (Sialic) (SIlica and ALuminum rich) u Diorite u Gabbro (Mafic) (MAgnesium and iron (FE) rich) u Dunite & Peridotite (Ultramafic) n Fine-Grained n Volcanic (Extrusive) u Rhyolite (Sialic) u Andesite u Basalt (Mafic)

Igneous Rock Identification n Granite (& Rhyolite) u High in Si + O u Low in Fe + Mg u Mostly feldspar & quartz u Light-colored n Basalt (& Gabbro) u “Low” in Si + O u High in Fe + Mg u no quartz, abundant ferromagnesian minerals u Dark colored n Andesite (& Diorite- intermediate)

COARSE-GRAINED PLUTONIC ROCK GRANITE

WEATHERING, EROSION, TRANSPORTATION n Weathering- Physical disintegration and chemical decomposition of rocks n Erosion- Physical removal n Transportation - Movement of eroded particles n Chemical vs. Physical Weathering

Physical Weathering

ROCK CYCLE

Relative Percentages of Sedimentary Rocks

SEDIMENT n Particle size u Pebbles, cobbles, boulders u Gravel- > 2mm u Sand- 2mm mm u Silt mm mm u Clay- < F Deposition Clay-sized particle vs. clay mineral

TYPES OF SEDIMENTARY ROCKS n Clastic or Detrital n Chemical- inorganic precipitation or evaporation n Biochemical- Organic remains u shells, charcoal, plant fragments

CLASTIC (Detrital) ROCKS n Breccia and Conglomerate (> 2mm) u Sedimentary Breccia- angular fragments u Conglomerate- rounded fragments n Sandstone (2mm mm) u Quartz sandstone u Arkose (feldspar) u Graywacke (appreciable amounts of silt/clay) F Fine-grained Matrix F Usually from turbidity currents

Quartz Sandstone

CHEMICAL SEDIMENTARY ROCKS n Carbonate Rocks u Limestone- made of calcite F Inorganic varieties micrite, oolites, travertine u Dolomite u Recrystallization n Chert- silica n Evaporites u Rock gypsum u Rock salt

MICRITE

OOLITES

Chert

BIOCHEMICAL SEDIMENTARY ROCKS n Coal u Develops from peat F plant fragments u Lignite u Bituminous Coal n Carbonate Rocks u Limestone- made of calcite F organic varieties Coquina Fossiliferous Limestone Chalk

Metamorphic Rocks n Metamorphism u Increase in Pressure; increase in Temperature F Burial F Contact F Regional n Metamorphic rock u Pre-existing rock u Parent rock

Foliation

Classification A- Slate C- Phyllite D- Schist E- Gneiss F- Migmatite

Classification