Rocks, Minerals & The Rock Cycle – Key Vocabulary

A comprehensive set of vocabulary flashcards covering fundamental terms related to rocks, minerals, and geological processes discussed in the lecture notes.

Rock

A naturally occurring solid aggregate of minerals, sometimes containing non-mineral particles.

Mineral

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

Rock Cycle

The continuous processes—melting, cooling, weathering, erosion, compaction, cementation, and metamorphism—that transform one rock type into another.

Igneous Rock

Rock formed through the cooling and solidification of magma or lava.

Intrusive (Plutonic) Igneous Rock

Igneous rock that solidifies below Earth’s surface, producing coarse (phaneritic) crystals; e.g., granite, diorite.

Extrusive (Volcanic) Igneous Rock

Igneous rock that cools rapidly at or near the surface, often glassy or fine-grained (aphanitic); e.g., basalt, rhyolite.

Magma

Molten rock beneath Earth’s surface that may cool to form intrusive igneous rocks.

Lava

Magma that has erupted onto Earth’s surface.

Felsic

Igneous composition rich in silica and lighter minerals; light-colored rocks like granite and rhyolite.

Mafic

Igneous composition low in silica but rich in iron and magnesium; dark-colored rocks like basalt and gabbro.

Intermediate Igneous Rock

Composition between felsic and mafic; examples include andesite and diorite.

Phaneritic Texture

Igneous texture with large, visible crystals formed by slow cooling underground.

Aphanitic Texture

Fine-grained igneous texture resulting from rapid cooling at the surface.

Porphyritic Texture

Igneous texture showing large crystals (phenocrysts) embedded in a fine-grained matrix.

Sedimentary Rock

Rock formed by deposition, compaction, and cementation of sediments or precipitation of minerals.

Clastic Sedimentary Rock

Sedimentary rock composed of rock fragments (clasts) cemented together; e.g., sandstone, shale.

Chemical Sedimentary Rock

Sedimentary rock formed by precipitation of minerals from solution; e.g., limestone, gypsum.

Organic (Biochemical) Sedimentary Rock

Rock formed from accumulation of biological debris; e.g., coal, chalk.

Compaction

Process in which sediment grains are pressed together under pressure, reducing pore space.

Cementation

Binding of sediment grains by minerals precipitated from groundwater, forming solid rock.

Metamorphic Rock

Rock produced from pre-existing rock altered by heat, pressure, or chemically active fluids.

Foliated Metamorphic Rock

Metamorphic rock displaying bands or layers due to directional pressure; e.g., slate, gneiss.

Non-Foliated Metamorphic Rock

Metamorphic rock lacking banding; minerals recrystallize without orientation; e.g., marble, quartzite.

Parent Rock (Protolith)

The original rock type that undergoes metamorphism to form a metamorphic rock.

Weathering

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

Erosion

Transport of weathered material by water, wind, ice, or gravity.

Sedimentation

Deposition of sediments from a transporting medium.

Lithification

The combined processes of compaction and cementation that turn sediments into rock.

Crystallization

The formation of mineral crystals as magma or lava cools.

Granite

Coarse-grained, felsic intrusive igneous rock common in continental crust.

Basalt

Fine-grained, mafic extrusive igneous rock forming most oceanic crust.

Andesite

Intermediate extrusive igneous rock typically associated with volcanic arcs.

Diorite

Intermediate coarse-grained intrusive igneous rock.

Gabbro

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

Rhyolite

Felsic extrusive igneous rock with high silica content; volcanic equivalent of granite.

Obsidian

Volcanic glass formed from rapid cooling of silica-rich lava.

Pumice

Light, porous volcanic rock formed during explosive eruptions; can float on water.

Scoria

Dark, vesicular volcanic rock rich in trapped gas bubbles.

Sandstone

Clastic sedimentary rock composed mainly of sand-sized particles.

Shale

Fine-grained clastic sedimentary rock formed from compacted clay.

Limestone

Sedimentary rock mostly of calcium carbonate; forms from shell debris or chemical precipitation.

Gypsum

Soft chemical sedimentary rock of calcium sulfate formed by evaporation.

Coal

Organic sedimentary rock derived from compressed plant material, rich in carbon.

Chalk

Soft, white limestone composed of microscopic marine organisms (coccolithophores).

Slate

Fine-grained foliated metamorphic rock originating from shale; splits into flat sheets.

Gneiss

Coarse-grained foliated metamorphic rock with alternating light and dark bands.

Marble

Non-foliated metamorphic rock formed from limestone; composed mainly of recrystallized calcite.

Quartzite

Hard, non-foliated metamorphic rock formed from sandstone; dominated by quartz.

Pegmatite

Very coarse-grained intrusive igneous rock often containing rare minerals and crystals.

Peridotite

Ultramafic intrusive igneous rock rich in olivine; major constituent of the upper mantle.

Grand Canyon

Arizona gorge exposing thick sequences of sedimentary rock layers that reveal Earth’s geological history.

Stonehenge

Prehistoric monument in England built of sandstone and bluestone, illustrating ancient use of rock materials.

Great Wall of China

Historic fortification constructed with local stones and bricks, demonstrating human utilization of geologic resources.