Earth Science: Earth Materials

Naturally Occurring

Formed through natural geologic processes.

Solid

Only solid crystalline substances are considered minerals.

Definite Chemical Composition

Should be expressed in a chemical formula.

Generally Inorganic

Formed by inorganic processes, not derived from organic materials.

Crystalline Structure

Atoms (Ions) are arranged in an orderly.

Orderly Packing of Atoms

Quartz

Consists of Silicon (Si) and Oxygen (O) atoms, (1:2).

Mineraloids

A naturally occurring, inorganic solid that does not exhibit crystallinity.

Pumice

It is ejected from the volcano in a sudden blast and cools so quickly that bubbles of gas are trapped within the amorphous glass.

Obsidian

A volcanic glass that cools so rapidly that atoms do not have time to arrange themselves into a crystalline solid.

Rock

Any solid mass of mineral, or mineral-like, matter that occurs naturally as part of our planet. Aggregate of minerals.

Atoms: Building Blocks of Minerals

• Most elements join with atoms of other elements to form chemical compounds.

• Few minerals are made entirely of atoms of only one element. (Copper, Sulfur, Diamond)

Native Gold

• Often found in stream deposits or as grains in igneous rocks.

• 50% of gold is used in jewelry.

• 40% is used for currency and investment.

• 10% is used in industry.

Luster

The appearance or quality of light reflected from the surface of a mineral.

Diaphaneity

The ability of mineral to transmit light. e.g. translucent, transparent, opaque.

Color

The most conspicuous characteristic of any mineral.

Streak

Color of a mineral in powdered form that is useful in identification.

Hardness

A measure of the resistance of a mineral to abrasion or scratching.

Brittle

Breaks, powders easily.

Malleable

Can be hammered into thin sheets.

Sectile

Can be cut into thin shavings with a knife.

Ductile

Can be stretched into a wire.

Flexible

Ability of being bent without breaking.

Elastic

Ability to restore in its form after deformation.

Cleavage

The tendency of a mineral to break along planes of weak bonding.

Fracture

Minerals that have chemical bonds that are equally, or nearly equally, strong in all directions.

Crystal Shape

• Fibrous

• Bladed

• Banded

• Cubic Crystals

Density / Specific Gravity

Represents the ratio of a mineral’s weight to the weight of an equal volume of water.

More Dense

More mass (matter) in a given volume.

Less Dense

Less mass (matter) in a given volume.

Other Properties of Minerals

• Taste

• Feel

• Smell

• Double Refraction

• Effervescence

Silicates

Contains the silicon-oxygen tetrahedron as their building block.

Non-Silicates

Minerals that do not contain silicon or oxygen.

Natural Resources

Classified as renewable when they can be replenished over short time spans and nonrenewable when they can’t.