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