Rocks & Minerals Lecture – Key Vocabulary

Vocabulary flashcards covering mineral properties, mineral groups, and rock stratification concepts from the lecture.

Luster

A mineral’s ability to reflect light from its surface.

Metallic Luster

Type of luster that looks shiny like metal.

Vitreous (Glassy) Luster

Luster that appears glass-like and reflective.

Dull (Earthy) Luster

Luster that shows little to no shine; looks soil-like.

Silky Luster

Luster that resembles the sheen of silk fibers.

Greasy Luster

Luster that looks as if the surface is covered with oil or grease.

Resinous Luster

Luster that resembles the appearance of resin or amber.

Ability to Transmit Light

Property describing whether a mineral is opaque, translucent, or transparent.

Color (Mineral Property)

Visible hue of a mineral; unreliable for identification because impurities can alter it.

Streak

The color of a mineral in powdered form, observed on unglazed porcelain.

Crystal Shape

The characteristic external form or combination of forms a crystal displays.

Tenacity

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

Hardness

Resistance of a mineral to scratching or abrasion.

Mohs Hardness Scale

Relative scale (1–10) ranking minerals from soft talc to hard diamond.

Cleavage

Tendency of a mineral to break along planes of weak atomic bonding.

Fracture

Irregular breakage of a mineral producing uneven surfaces.

Specific Gravity

Ratio of a mineral’s density to the density of water.

Special Properties (Minerals)

Uncommon traits such as taste, odor, magnetism, fluorescence, radioactivity, or reactivity.

Silicate Minerals

Largest class of rock-forming minerals composed of silicon–oxygen groups; ~90 % of Earth’s crust.

Nonsilicate Minerals

Minerals lacking SiO₂; less abundant but often economically important.

Mica

Sheet-silicate mineral group known for perfect cleavage into thin flexible sheets.

Amphibole

Chain-silicate mineral family common in igneous and metamorphic rocks.

Pyroxene

Single-chain silicate mineral group found in many mafic igneous rocks.

Olivine

Isolated-tetrahedra silicate mineral, typically green, common in mantle rocks.

Stratified Rocks

Rocks that display distinct horizontal layers which can be easily split; mostly sedimentary.

Unstratified (Massive) Rocks

Rocks that show no visible layering.

Stratification

Process of horizontal sediment deposition and vertical stacking through time.

Sedimentation

First stage of stratification where eroded materials settle out of water or air.

Compaction

Stage where accumulating sediments are pressed together by overlying weight.

Cementation

Final stage where minerals (e.g., ocean salts) glue compacted sediments into solid rock.

Clastic Sedimentary Rocks

Sedimentary rocks formed from lithified fragments of pre-existing rocks.

Biological Sedimentary Rocks

Sedimentary rocks formed from the remains of once-living organisms.

Chemical Sedimentary Rocks

Sedimentary rocks formed from mineral precipitation out of solution.

Sedimentary Rocks

Rocks created from compressed or chemically precipitated deposits, often in strata near Earth’s surface.

Typical Sedimentary Environments

Settings like riverbeds, oceans, ponds, coasts, deserts, and caves where sediments accumulate.

Fault (in Stratified Rocks)

Crack in layered rock—often on the ocean floor—exposing strata for study.