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MINERALS
Chemical composition of the Crust Oxygen most abundant- 46.6% Followed by silicon and aluminum Iron, Calcium, Sodium,
Potassium, Magnesium The most common minerals will
be composed mostly of these elements
Silica & silicates
MINERAL vs. ROCK ROCK
An aggregate of one or more MINERALS (usually- coal, organic)
MINERAL Solid Crystalline- orderly arrangement of atoms Naturally occurring Inorganic Definite chemical composition
e.g. SiO2 for quartz; KAlSi3O8 for feldspar
Atom & Elements Atoms
Neutral Nucleus
Proton, neutron Electron
Ions Electrical Charge
Molecule- e.g. water molecule
Chemical activity Stable atoms want
positive & negative charges balanced electron shells full
Ions- positive (Cations) and negative (Anions) Bonding
Ionic Covalent Metallic Van der Waal’s
Element
Atomic number Number of PROTONS
Isotope Differing number of
NEUTRONS Atomic weight
Mass of PROTONS and NEUTRONS
Crystallinity 3 dimensional orderliness of atoms Silicon-oxygen tetrahedron Silicate structures
Single- e.g. olivine Chain
Single chain- pyroxene Double chain- amphibole
Sheet- e.g. mica, clay Framework- e.g. quartz, feldspar
MINERALS
Crystalline solids Natural and Inorganic Substances Definite chemical composition
Can be written as a chemical formula
Solid solution (within a range)
Important Minerals
Quartz (most abundant) FELDSPAR Group
Potassium Feldspar - Orthoclase Plagioclase Feldspar
Sodium (Na) Albite Calcium (Ca) Anorthosite
Important Minerals
PYROXENE Group- Augite most common
AMPHIBOLE Group- Hornblende most common
MICA Group- Si + O in sheets Biotite Muscovite
CALCITE- CaCO3
Properties of Minerals Color
Not always reliable (Olivine, green; Flourite, yellow, purple, green…)
Ferromagnesian minerals green or black Streak- powdered form Luster- reflectance of light
Metallic Nonmetallic
Vitreous or Glassy Earthy
Properties of Minerals Hardness- resistance to scratching Moh’s Hardness Scale
Fingernail = 2.5 Penny = 3.5 Knife/Glass = 5.5 Streak Plate= 6.5
Properties of Minerals
Cleavage Quality (poor, good, perfect) Number of directions
One- e.g. Mica Two at right angles- e.g. Feldspar, Pyroxene Two not at right angles- e.g. Amphibole Three at right angles (cubic)- e.g. Halite Three not at right angles (rhombohedral)- e.g.
calcite Four (Flourite) or six (Sphalerite)- not common
Properties of Minerals
Fracture Absence of cleavage Irregular fracture Conchoidal fracture- Quartz
Density Specific Gravity
Some unusual properties Striations, Magnetism, Taste, Odor, Double
refraction
Chemical tests
Reaction with HCl Calcite effervesces
Mineral Groups
Silicates Carbonates Oxides Sulfides Sulfates Native Elements Halides
Silicates
Quartz Feldspar
Plagioclase Orthoclase
Micas Muscovite Biotite
Amphibole (Hornblende) Pyroxene (Augite) Olivine
Carbonates
Calcite (calcium carbonate) Dolomite (calcium-magnesium
carbonate) Both are used as Portland Cement
Oxides
Hematite (iron oxide) Iron ore, pigment
Magnetite Iron ore
Corundum (aluminum oxide) Sapphire, ruby (gemstone) Abrasive
Sulfides
Galena (Lead sulfide) Lead ore
Sphalerite Zinc sulfide) Zinc ore
Pyrite (Iron sulfide) Sulfuric acid
Chalcopyrite (Copper Iron sulfide) Copper ore
Sulfates
Gypsum Anhydrite Both use in plaster
Native Elements
Gold- trade, instruments Silver- photography, conductors Copper- electrical Platinum- catalysts Sulfur- chemicals, pharmaceuticals Diamond- carbon
Gemstone, abrasive Graphite- carbon
Lubricant, pencils
Minerals as Resources
Reserves: Minerals that can be extracted at a profit under current economic and technological conditions
Ores: metallic minerals Industrial Rocks or Minerals: non
metallic minerals (phosphate) Aggregates: crushed rock
ROCK CYCLE
Equilibrium Interrelationships between
igneous rocks sediment sedimentary rocks metamorphic rocks weathering and erosion