Minerals – Key Vocabulary

20 vocabulary flashcards summarizing essential mineral concepts, properties, and groups.

Mineral

A naturally-occurring, inorganic, homogeneous solid with a definite chemical composition and an ordered crystalline structure.

Rock-forming mineral

A mineral that is common and abundant in Earth’s crust and serves as a basic building block of rocks.

Luster

The quality and intensity of light reflected from a mineral’s surface; can be metallic or non-metallic.

Metallic luster

Type of luster where the mineral is opaque and shines like polished metal (e.g., pyrite, galena).

Non-metallic luster

Luster categories such as vitreous, pearly, silky, resinous, greasy, dull, etc., shown by minerals that do not appear metallic.

Hardness

A mineral’s resistance to scratching or abrasion, measured by the Mohs scale from 1 (talc) to 10 (diamond).

Mohs Scale of Hardness

Field test scale (1–10) created by Friedrich Mohs to compare scratch resistance of minerals.

Crystal Form (Habit)

The external shape a crystal displays as it grows, reflecting its internal atomic arrangement (e.g., prismatic, tabular).

Color

The visible hue of a mineral in hand specimen; can vary widely due to impurities or weathering.

Streak

The color of a mineral in powdered form, obtained by scratching it on unglazed porcelain; more diagnostic than bulk color.

Cleavage

The tendency of a mineral to break along flat, planar surfaces where atomic bonding is weaker.

Specific Gravity (SG)

The ratio of a mineral’s density to the density of water; indicates how many times heavier the mineral is than an equal volume of water.

Silicates

Largest mineral group composed of silicon-oxygen tetrahedra; includes over 90 % of rock-forming minerals.

Oxides

Minerals in which oxygen anions combine with one or more metal cations (e.g., hematite, magnetite).

Sulfates

Minerals containing the sulfate anion (SO₄)²⁻ bonded to metals (e.g., gypsum, anhydrite).

Sulfides

Minerals composed of sulfur combined with metals; important ore sources (e.g., pyrite, galena, chalcopyrite).

Carbonates

Minerals containing the carbonate anion (CO₃)²⁻, such as calcite and dolomite.

Native elements

Minerals consisting of a single element, subdivided into metals, semi-metals, and nonmetals (e.g., gold, bismuth, sulfur).

Halides

Minerals in which halogen elements (Cl, F, Br, I) bond with metals, such as halite (NaCl) and fluorite (CaF₂).

Brittleness

A mechanical property where a mineral breaks or powders easily when struck, lacking flexibility or malleability.