GEOL 333 #1 - Introduction to Minerals, Soils, and Rocks

Earth materials = minerals, rocks, and soils

A) Mineral - must satisfy all 5 parts of definition to be a mineral.

Naturally occurring - occurs in nature (not synthetic)

Inorganic - not organic chemical (carbon-based compound, usually produced by organisms).

Solid - not liquid or gas

Definable chemical composition - contains elements bonded together in definite proportions (and can write mineral chemical formula), e.g., quartz SiO2, ratio of Si:O = 1:2

Crystal structure - Orderly arrangement of atoms. Glass has random arrangement of atoms (amorphous).

Mineralogy = science and study of minerals

B) Rock = coherent and relatively hard, naturally formed mass of mineral matter.

Petrology = science and study of rocks (petra = Greek for rock)

C) Soil = layer of sediment (loose grains) and organic matter that covers most of Earth's surface, produced by weathering (physical, chemical and biological processes that break down solid rock), can support plant growth.

Pedology = science and study of soils (pedon = Greek for ground)

D) Environment = our surroundings; Geology (link #2) = Scientific study of solid Earth; Environmental Geology = applied geology, Use of geological information to understand and help to solve certain societal problems.

E) Importance of Mineralogy, Petrology, and Pedology

1) Natural Earth Resources (Minerals, Rocks, Energy, and Soil) - Minerals and rocks are used extensively as resources for everyday life. Most minerals are non-renewable resources, i.e., consumed at much faster rate than created by nature. Eventually we will run out of many minerals used today. Mineral/rock resources = metals (e.g., Fe, Al, Au, Cu), and non-metals for industry/agriculture (phosphates, nitrates, salt, sulfur), construction (crushed stone, sand, gravel, clay, limestone, gypsum), and ceramics/abrasives/gems (e.g., feldspar, quartz, corundum, diamonds, rubies, emeralds). Mineral and Rock consumption in USA >10 tons of earth materials per person per year. Mineral deposits can be beautiful, e.g., giant crystals from Mexico's Cave of the Crystals (link #2, #3, #4, #5, #6, #7, photos)

Soils are greatest resource of many countries; world gets food supply from crops grown on soils.

Many forms of energy are in rocks (e.g., oil and natural gas, coal, uranium, etc.). Geology-related energy consumption in USA is ~11 tons per person per year.

Rock/mineral use through history - earliest known use of minerals (~50,000 years ago) was flint (fine-grained quartz) for knifes, arrowheads; other important minerals = pigments - Mn- and Fe-oxides (art), salt (food preservation), metals (bronze; steel), stone (pyramids).

Need to reduce environmental impact of mining (Stark photos involving resource extraction).

Other environmental issues involving earth materials will be identified by students at the beginning of next class (Jan. 22).