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

Minerals as Resources n Reserves: Minerals that can be extracted at a profit under current economic and technological conditions n Ores: metallic minerals n Industrial Rocks or Minerals: non metallic minerals (phosphate) n Aggregates: crushed rock

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