Minerals: Key Vocabulary and Concepts

Vocabulary flashcards covering definitions and key properties of minerals, their physical tests, and major chemical groups.

Mineral

A naturally formed, generally inorganic solid with an ordered crystalline structure and a specific chemical composition that can be expressed by a chemical formula.

Rock-forming minerals

Common, abundant minerals that make up most of Earth’s crust and serve as the fundamental building blocks of rocks.

Five characteristics of a mineral

(1) Naturally formed, (2) generally inorganic, (3) solid, (4) crystalline structure, (5) definite chemical composition.

Luster

The quality and intensity of light reflected from a mineral’s surface.

Metallic luster

Opaque, highly reflective shine similar to polished metal; shown by minerals like gold, silver, and copper.

Non-metallic luster

Includes vitreous (glassy), adamantine, resinous, silky, pearly, dull (earthy), greasy, and other non-metal appearances.

Hardness

A mineral’s resistance to scratching or abrasion.

Mohs scale of hardness

Ten-point scale (1 = talc to 10 = diamond) ranking minerals by their ability to scratch those of lower number.

Crystal form (habit)

External shape of a crystal determined by its internal atomic arrangement.

Amorphous

Describes a substance lacking an ordered crystal structure.

Color (of a mineral)

Visible hue of a mineral, often variable due to impurities and weathering.

Streak

Color of a mineral in powdered form, usually more diagnostic than surface color.

Cleavage

Tendency of a mineral to break along specific planes of weakness, producing smooth, flat surfaces.

Specific gravity

Ratio of a mineral’s density to the density of water; effectively its relative weight.

Odor (mineral property)

Smell emitted by some minerals (e.g., sulfur’s distinct odor).

Taste (mineral property)

Flavor detected when a mineral is placed on the tongue (e.g., halite tastes salty).

Magnetism

Attraction to a magnet exhibited by minerals such as magnetite.

Tenacity

A mineral’s resistance to breaking, bending, cutting, or deforming.

Reaction to acid

Effervescence or fizzing when a mineral (e.g., calcite) contacts dilute acid, indicating carbonate content.

Silicates

Minerals containing silicon and oxygen arranged as silicon-oxygen tetrahedra; make up over 90 % of rock-forming minerals.

Silicon-oxygen tetrahedron

Basic structural unit of silicate minerals consisting of one silicon atom bonded to four oxygen atoms in a tetrahedral shape.

Oxides

Minerals composed of oxygen anions (O²⁻) combined with one or more metal ions.

Sulfates

Minerals containing the sulfate anion (SO₄)²⁻ combined with metals.

Sulfides

Minerals of sulfur combined with metals; important ores of copper, lead, zinc, etc.

Carbonates

Minerals containing the carbonate anion (CO₃)²⁻ combined with other elements.

Native elements

Minerals consisting of a single element in pure form.

Metals and intermetals (native)

Highly conductive native elements with metallic luster and generally low hardness, e.g., gold, lead.

Semi-metals (native)

Fragile native elements with moderate to low conductivity, e.g., arsenic, bismuth.

Nonmetals (native)

Non-conductive native elements such as sulfur and diamond.

Halides

Minerals in which halogen elements (Cl, F, Br, I) combine with one or more metals.