Rocks, Minerals, and the Rock Cycle – Key Vocabulary

These vocabulary flashcards cover fundamental terms and concepts about rocks, minerals, their formation processes, properties, and extraction methods as presented in the lecture notes.

Rock

A naturally occurring aggregate of minerals and/or other rock fragments.

Mineral

A naturally occurring inorganic solid with a definite chemical composition and an ordered atomic structure.

Ore

A mineral deposit that contains enough metal to be mined profitably.

Igneous Rock

Rock formed by the cooling and solidification of molten rock (magma or lava).

Intrusive (Plutonic) Rock

Igneous rock that crystallizes slowly below Earth’s surface, producing coarse grains.

Extrusive (Volcanic) Rock

Igneous rock that cools quickly at the surface, producing fine-grained textures.

Sedimentary Rock

Rock produced by the lithification of weathered and eroded particles at or near Earth’s surface.

Metamorphic Rock

Rock formed from pre-existing rock altered by intense heat and/or pressure without melting.

Magma

Molten rock beneath Earth’s surface.

Lava

Molten rock erupted onto Earth’s surface.

Lithification

The physical and chemical processes (compaction and cementation) that transform sediments into sedimentary rock.

Weathering

The breakdown of rocks at Earth’s surface by physical or chemical processes.

Erosion

The movement of weathered material by wind, water, ice, or gravity.

Deposition

The laying down or settling of transported sediments.

Cementation

Process in which dissolved minerals precipitate between sediment grains, binding them together.

Rock Cycle

Model describing the formation, alteration, destruction, and re-formation of rocks through geologic processes.

Felsic

Igneous composition rich in silica and light-colored minerals such as quartz and feldspar.

Mafic

Igneous composition rich in magnesium and iron, producing dark-colored minerals such as pyroxene and olivine.

Intermediate

Igneous composition between felsic and mafic in silica content and color.

Granite

Coarse-grained intrusive felsic igneous rock composed mainly of quartz and feldspars.

Basalt

Fine-grained extrusive mafic igneous rock; Earth’s most abundant volcanic rock.

Rhyolite

Fine-grained extrusive felsic igneous rock, volcanic equivalent of granite.

Andesite

Fine-grained extrusive intermediate igneous rock.

Gabbro

Coarse-grained intrusive mafic igneous rock, plutonic equivalent of basalt.

Diorite

Coarse-grained intrusive intermediate igneous rock.

Pegmatite

Very coarse-grained igneous rock that crystallizes from water-rich magma.

Peridotite

Ultramafic intrusive rock composed mainly of olivine; dominant in Earth’s mantle.

Clastic Sedimentary Rock

Sedimentary rock made of fragments (clasts) of pre-existing rocks cemented together.

Chemical Sedimentary Rock

Rock formed from minerals precipitated directly from solution (e.g., rock salt, chert).

Organic (Bioclastic) Sedimentary Rock

Rock composed of accumulated biological material, such as shells or plant remains (e.g., limestone, coal).

Conglomerate

Clastic sedimentary rock with rounded gravel-size clasts.

Breccia

Clastic sedimentary rock with angular gravel-size clasts.

Sandstone

Clastic sedimentary rock dominated by sand-size grains (63 μm–2 mm).

Shale

Fine-grained clastic sedimentary rock that splits easily into thin layers (fissile).

Mudstone

Fine-grained clastic sedimentary rock that breaks into blocks, lacking fissility.

Siltstone

Clastic sedimentary rock composed mainly of silt-size particles.

Chert

Hard, microcrystalline chemical sedimentary rock composed of quartz.

Gypsum

Chemical sedimentary rock composed of calcium sulfate dihydrate; common evaporite.

Rock Salt (Halite)

Chemical sedimentary rock composed of sodium chloride formed by evaporation.

Travertine

Calcium-carbonate chemical sedimentary rock precipitated from hot-spring or cave waters.

Coal

Organic sedimentary rock formed from compressed plant remains.

Chalk

Soft, porous limestone formed from microscopic calcareous shells.

Slate

Low-grade, fine-grained foliated metamorphic rock derived from shale.

Schist

Medium-grade foliated metamorphic rock with visible platy minerals.

Gneiss

High-grade foliated metamorphic rock with banded light and dark minerals.

Migmatite

Mixed metamorphic-igneous rock showing partial melting.

Blueschist

High-pressure, low-temperature metamorphic rock rich in blue amphibole (glaucophane).

Recrystallization

Metamorphic process where minerals change size or shape without melting.

Metamorphic Grade

Intensity of temperature and pressure conditions experienced during metamorphism.

Mohs Hardness Scale

Relative scale (1–10) ranking minerals by resistance to scratching.

Hardness

Mineral property describing resistance to being scratched.

Streak

Color of a mineral’s powdered form obtained on a streak plate.

Luster

The way light reflects from a mineral’s surface (metallic, vitreous, etc.).

Cleavage

Tendency of a mineral to break along flat, even planes of weakness.

Fracture

Irregular breakage of a mineral where cleavage is absent (e.g., conchoidal in quartz).

Density

Mass per unit volume of a substance; diagnostic for some minerals.

Crystal Form

External shape of a crystal reflecting its internal atomic arrangement.

Corundum

Aluminum-oxide mineral (Al₂O₃); varieties include ruby and sapphire.

Metallic Mineral

Mineral containing metal elements, often lustrous and ductile (e.g., hematite, chalcopyrite).

Non-Metallic Mineral

Mineral lacking metal elements; typically dull or earthy (e.g., gypsum, halite).

Bauxite

Principal ore of aluminum composed of hydrous aluminum oxides.

Hematite

Iron-oxide mineral (Fe₂O₃); major iron ore.

Fluorite

Calcium-fluoride mineral (CaF₂) often fluorescent; source of fluorine.

Chalcopyrite

Copper-iron sulfide mineral (CuFeS₂); primary copper ore.

Surface Mining

Extraction of mineral deposits near Earth’s surface (e.g., open-pit, strip, dredging).

Underground Mining

Extraction of ore bodies located deep below the surface via shafts and tunnels.

Open-Pit Mining

Surface mining method that removes ore by excavating a large pit.

Alluvial Mining

Recovery of valuable minerals from stream or river sediments, often by panning.

Dredging

Surface mining technique using floating equipment to scoop sediments from water bodies.

Sustainable Natural Resource Management

Using and extracting resources responsibly to ensure availability for future generations.