Mineral - any naturally formed, solid chemical element or compound that has a definite composition and crystalline structure
Rock - any natural, solid aggregate material, usually made of minerals
All minerals are rocks, but not all rocks are made of minerals
Quartz Granite

•Chemical composition
•Crystalline shape
•Hardness
•Color
•Streak
•Luster
•Cleavage
•Fracture
•Specific Gravity
•Magnetism
These properties are used to identify different minerals

Extremely important for the minerals industry. Often want an element or compound in mineral, and not necessarily the mineral itself
Ex.: iron and sulfur from iron pyrite (FeS
2
)
Identifying a mineral by chemical composition requires submitting a sample for chemical analysis; can be time consuming and expensive

Useful for identification; of little use for industry, as crystalline shape can be replicated in lab
Shape normally determined by chemical formula
Jewelry about the only use for this property; even then, the fact that crystals can be artificially created means that their value is artificial, as well
Hope Diamond

Mho’s Scale
1 = Talc
2 = Gypsum
3 = Calcite
4 = Fluorite
5 = Apatite
6 = Orthoclase
7 = Quartz
8 = Topaz
9 = Corundum
10 = Diamond
Relative scale based upon what mineral will scratch what mineral
Ex. Orthoclase will scratch apatite, but quartz will scratch orthoclase
Fingernail is about a 2.5; steel nail = 5.5
Diamond is hardest, which means that it does have some industrial application
Hardness does not relate to elemental scarcity or value

Color - what color unmolested mineral appears to be
Streak - color of ground mineral
These two can be radically different.
Ex.: Iron pyrite color is gold (fool’s gold); streak is black
Hematite is black/gray; streak is red-brown
Color is unreliable as identifier since impurities can change it; streak is more reliable

Depending upon mineral, will use a variety of other identifiers
Magnetism - used to identify iron ores
Cleavage - used to identify minerals like mica and gypsum that form crystals that loosely bond together
Fracture - helps to identify minerals with crystalline shapes that do not cleave

Based upon the key elements in the chemical composition, minerals are grouped into subcategories
•Silicates (feldspars, garnets, micas, olivine, quartz, clay minerals)
•Native Elements (diamond, sulfur, gold)
•Sulfides (galena, pyrite, millerite, sphalerite)
•Sulfates (barite, celestite, gypsum, secondary sulfates)
•Oxides (goethite, hematite, ilmenite, limonite, uranium minerals)
•Carbonates (calcite, dolomite, other iron-carbonate and others)
•Phosphates (apatite, vivianite, pyromorphite)
•Halides (fluorite, halite)

The largest group of minerals (30% of all minerals; 90% of whole crust); defined by having SiO
4 tetrahedra
Includes some gemstones such as tourmaline and topaz
Also has useful minerals such as talc, kaolin, and mica
Rocks made from silicates very useful for road and building materials

Contains all of the metals (gold, silver, copper, etc.) and metal alloys
Also includes diamonds and graphite (carbon)
Rare to find elements in their natural state; oftentimes, a primary method of metal extractions is from some other class
Ex. Copper and lead from sulfide minerals

Defn. - resources that a country uses, but cannot produce enough to meet demand
If cannot guarantee supply, economy could be hurt if supplies cut; Ex. OPEC oil embargo of 1973
Wealthy nations try to stockpile surplus to act as buffer against outside forces affecting economy

Vulcan Materials pit mine, Kennesaw, GA, 1993
Hollywood image of old man with mule, pick axe, and dynamite all but disappeared
Most economic mining done on huge scale with big equipment
•Open pit - dig deep into the ground, exposing new rock to surface
•Stripmining - shallow mine over large area
•Underground mining - tunnels

Mineral ore dug from deep hole created in the surface.
Walls of pit have roads built into them for cranes, trucks, etc. to be able to get to bottom
Economics of recovery have to constantly be re-evaluated, as hole must get wider as go deeper (walls are the road system)

Differs from open pit in horizontal extant
Stripmines are going after near horizontal seam of materials that are near the surface
Overburden is stripped from seam, and then mineral is extracted
Once mineral removed, overburden put back on top
Federal law now requires remediation

Pickaxe and dynamite have been replaced by large tunneling equipment that does the job safer and faster
Must leave some pillars of material behind, lest a cave-in ensue
Most dangerous form of mining
Miner safety in jeopardy from cave-ins and dust (black lung disease)

Hydraulic mining - sediments are blasted from hillside with water jets; sediment is sent through sluice boxes; not done much in U.S., but is done many other places (South America)
Dredging - similar to hydraulic mining, with the exception being that the sediment is scooped out of the ground instead of being blasted out with water

•Water passing through mine leaches toxic chemicals
•Tailings piles and ponds erode and contain toxics
•Processing chemicals are toxic and sometimes released
•Land slumpage when cave-ins occur
•Underground fires can burn for decades
•Many mines are abandoned when economics fail
•Energy used for entire process is large
Pictures from Berkeley Pit in Butte Montana
Superfund Sites

Some rocks and minerals take very little processing
Ex: crushed rock for roads and construction material
Others take an incredible amount of energy and produce great quantities of waste
Smelting - heating metal ores to extreme temperature to release metal; gaseous vapors are toxic and often acidic
Leach extraction - pour acid or base on crushed piles of ore, extract metal from leachate by electrolysis; crushed ore is left to contaminate water supply when finished, with acid or base still present

•Besides saving environmental damage for extraction and processing, can save huge quantities of energy
•Recycling aluminum saves 95%
•Recycling glass saves 25%
•Recycling steel saves between 60-75%
•Recycling plastic saves 33% of the energy needed to make them from virgin materials
Recycling just one aluminum can will save enough energy to run a 100W lightbulb for 20 hours