Rocks, Minerals, and the Rock Cycle (Geotechnical Engineering)

Vocabulary flashcards covering minerals, rocks, rock types, the rock cycle, and key properties relevant to geotechnical engineering.

Mineral

Building blocks of rocks; naturally occurring inorganic crystalline substances with fixed chemical composition and ordered atomic structure (e.g., silica, mica, sodium chloride).

Rock

A natural aggregate composed of one or more minerals; the larger-scale material formed from minerals.

Aggregate

The combination of one or more minerals, or mixtures of other rocks, that makeup a rock.

Non-crystalline mineral-like material

Mineral-like substances lacking long-range crystalline order, such as opal, obsidian, glass, and coal.

Crystal structure

The regular, repeating arrangement of atoms within a mineral.

Hardness

The resistance of a mineral to scratching or abrasion; commonly assessed on the Mohs scale.

Mohs scale

A relative 1–10 scale ranking minerals by hardness; diamond is the hardest, talc the softest.

Hardness (definition)

The resistance of a mineral to abrasion or scratching.

Cleavage

The tendency of a mineral to break along planes of weakness in its crystal structure.

Planes of weakness

Specific crystallographic directions along which minerals preferentially split.

Solubility

The tendency of minerals to dissolve in water or acids; calcite dissolves in acid, causing observable effervescence.

Calcite

A carbonate mineral that dissolves in acid and shows effervescence; common in limestone.

Carbonate mineral

Minerals containing carbonate (CO3) groups, such as calcite.

Weathering

Physical and chemical breakdown of rocks at the surface, producing sediments and soils.

Sediment

Particles derived from weathering that are deposited and can become lithified into sedimentary rock.

Sedimentary rock

Rock formed from accumulated and lithified sediments (e.g., sandstone, limestone, claystone).

Igneous rock

Rock formed from cooling magma or lava, either underground (intrusive) or at the surface (extrusive).

Metamorphic rock

Rock formed when existing rocks are transformed by heat and pressure, causing changes in texture and mineral composition.

Rock cycle

The ongoing process by which rocks are formed, broken down, and transformed among igneous, sedimentary, and metamorphic forms through weathering, burial, heating, and melting.

Parent rock

The original rock that undergoes weathering, burial, or melting to form new rocks (e.g., magma forms igneous rock).

Soil

Young, weathered rock material; typically much younger than the parent rock (often tens of thousands to a few million years old).

Relative age

The age of rocks relative to other rocks, not an absolute date; Earth is about 4.5 billion years old.

Volcanic rock

Igneous rock formed from lava reaching the surface; typically among the younger rocks.

Plane of weakness

A plane along which rocks or minerals are prone to fracture due to crystal structure.

La Cucaracha shell

An example from the Panama Canal illustrating a plane of weakness that caused slope stability issues during excavation.