Minerals and Rocks – Vocabulary Review

Vocabulary flashcards covering definitions and key examples of minerals, their physical and chemical properties, and the three main rock types with representative examples.

Mineral

A naturally formed, generally inorganic crystalline solid with a definite chemical composition; building block of rocks.

Mineralogy

Branch of geology that studies minerals, their properties, formation, and distribution.

Rock

A natural substance composed of one or more mineral aggregates held together by natural processes.

Igneous Rock

Rock crystallized from magma or lava that cooled and solidified (e.g., granite, basalt).

Sedimentary Rock

Rock formed from the deposition, compaction, and lithification of sediments or biological material (e.g., limestone, sandstone).

Metamorphic Rock

Rock resulting from alteration of pre-existing igneous or sedimentary rocks by heat, pressure, or chemically active fluids (e.g., slate, gneiss).

Magma

Molten or partially molten rock beneath Earth’s surface.

Lava

Molten rock that has reached Earth’s surface.

Clastic Sedimentary Rock

Sedimentary rock made of lithified fragments of pre-existing rocks; classified by dominant grain size.

Non-clastic Sedimentary Rock

Sedimentary rock formed from chemical precipitation or biological accumulation (e.g., gypsum, chalk).

Cleavage

Tendency of a mineral to break along planes of weak atomic bonding, producing flat surfaces.

Fracture

Irregular breakage of a mineral that lacks cleavage; conchoidal fracture is curved breakage seen in quartz.

Hardness

Resistance of a mineral to scratching, commonly measured by Mohs scale.

Streak

Color of a mineral’s powdered form, obtained by rubbing it on unglazed porcelain.

Color (Mineral)

Visible hue of a mineral; often unreliable alone for identification.

Luster

Appearance of a mineral’s surface in reflected light; classified as metallic or non-metallic.

Metallic Luster

Shiny, reflective surface resembling polished metal (e.g., pyrite, galena).

Non-metallic Luster

Luster not resembling metal; categories include vitreous, silky, earthy, etc.

Transparency (Diaphaneity)

Degree to which light passes through a mineral—transparent, translucent, or opaque.

Specific Gravity

Ratio of a mineral’s density to that of water; indicates relative heaviness.

Tenacity

Mineral’s resistance to breaking, bending, or tearing (e.g., brittle, malleable, flexible).

Magnetism (Mineral)

Ability of a mineral to attract or repel other materials (e.g., magnetite).

Crystal Lattice

Regular three-dimensional arrangement of atoms in a crystalline solid.

Amorphous Solid

Solid lacking a long-range crystal lattice; atoms arranged randomly.

Conchoidal Fracture

Smooth, curved fracture surface resembling broken glass; characteristic of quartz and obsidian.

Sheety Cleavage

Layered cleavage allowing minerals to split into thin sheets, common in mica (muscovite, biotite).

Rhombohedral Cleavage

Three-directional cleavage forming rhomboid shapes, typical of calcite.

Silicate Class

Largest mineral group containing silicon and oxygen tetrahedra (e.g., quartz, feldspar, olivine).

Carbonate Class

Minerals containing carbonate ion (CO₃)²⁻; often marine deposits (e.g., calcite, dolomite).

Sulfate Class

Minerals with sulfate ion (SO₄)²⁻; form in evaporative environments (e.g., gypsum, barite).

Halide Class

Minerals composed of halogen elements with metals; natural salts (e.g., halite, fluorite).

Oxide Class

Minerals where oxygen combines with metals; record magnetic history (e.g., hematite, magnetite).

Sulfide Class

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

Phosphate Class

Minerals containing phosphate ion (PO₄)³⁻; biological importance in bones and teeth (e.g., apatite).

Native Element Class

Minerals consisting of single elements or natural alloys (e.g., gold, copper, graphite).

Quartz

Common silicate mineral (SiO₂) exhibiting conchoidal fracture and vitreous luster; may appear as rose quartz.

Halite

Sodium chloride mineral (NaCl) with cubic cleavage; common rock salt.

Fluorite

Calcium fluoride mineral (CaF₂) with octahedral cleavage; exhibits fluorescence.

Calcite

Calcium carbonate mineral (CaCO₃) showing rhombohedral cleavage and double refraction.

Pyrite

Iron sulfide mineral (FeS₂) with metallic luster; known as “fool’s gold.”

Galena

Lead sulfide mineral (PbS) possessing high density and metallic luster; primary lead ore.

Coal

Organic sedimentary rock derived from accumulated plant material; major energy source.

Slate

Fine-grained foliated metamorphic rock derived from shale; exhibits slaty cleavage.

Phyllite

Metamorphic rock between slate and schist, displaying a silky sheen from fine mica minerals.

Schist

Medium- to coarse-grained foliated metamorphic rock rich in micas; forms at higher metamorphic grades.

Gneiss

High-grade metamorphic rock with banded appearance due to mineral segregation.

Basalt

Fine-grained mafic igneous rock formed from rapid cooling of lava; major oceanic crust component.

Granite

Coarse-grained felsic igneous rock composed mainly of quartz, feldspar, and mica.

Pumice

Highly vesicular, lightweight volcanic glass formed from gas-rich explosive eruptions; floats on water.

Obsidi​an

Natural volcanic glass with conchoidal fracture formed by rapid cooling of high-silica lava.

Tuff

Igneous rock formed from consolidated volcanic ash ejected during explosive eruptions.