Geology, Mineralogy, and the Rock Cycle

Flashcards created from lecture notes covering geologic timescale, solar system origins, mineral classification, rock types, physical properties, and stress-strain concepts.

Nebular Hypothesis

The theory that the solar system formed from a cloud of gas and dust, eventually flattening into a disk, with the planets and sun clumping into their present forms.

Mineral

A naturally occurring, inorganic, solid element or compound with a definite chemical composition and a regular internal crystal structure.

Cleavage

The tendency of a mineral to break along particular planes of weakness.

Silicates

The most abundant mineral group, composed of minerals containing silicon and oxygen, such as quartz ($SiO_2$) and various feldspars.

Ferromagnesian Silicates

Silicate minerals containing iron and/or magnesium, which are dark in color and more susceptible to dissolution/weathering than other silicates.

Non-Silicates

Minerals that contain no silicon, categorized into major groups such as oxides, carbonates, sulfates, sulfides, halides, and native elements.

Plutonic (Intrusive) Igneous Rocks

Igneous rocks that form from magma deep below the surface in a magma chamber and cool slowly, allowing larger crystals to form that are visible to the naked eye.

Volcanic (Extrusive) Igneous Rocks

Igneous rocks that form from lava erupted onto the Earth's surface and cool rapidly, resulting in much smaller crystal sizes where individual crystals are often visible only with magnification.

Metamorphic Rocks

Rocks formed from preexisting rocks of any type that are exposed to extreme heat and pressure within the Earth without total melting.

Foliated Texture

A texture typical of many metamorphic rocks resulting from recrystallized minerals aligning in parallel bands or planes under heat and pressure.

Sediment

Loose material deposited at the surface of the Earth by water, air, ice, or gravity at low temperature and pressure.

Clastic Sedimentary Rock

A rock formed from sediments cemented together by minerals (such as quartz, calcite, iron minerals, or clays) that form between the grains.

Clastic (Terrigenous) Sediments

Sediments consisting of alumino silicate minerals derived from mechanical weathering, including quartz, feldspar, and clay minerals.

Chemical Sediments

Sediments precipitated directly from seawater, river water, spring water, or lake water through chemical weathering processes.

Biogenic Sediments

Sediments composed of carbonates or silica derived from the shell-making activity of marine or freshwater organisms.

Porosity

The proportion of void space in a rock, sediment, or soil.

Permeability

The degree to which pores or cracks in a geologic material are interconnected, allowing fluids to migrate through it.

Compressive Stress

A force that applies squeezing to geologic materials.

Tensile Stress

A force that pulls geologic materials apart.

Shear Stress

A force where different parts of a material are moved in different directions across a plane.

Strain

Deformation in geologic materials that results from applied stress.

Elastic Deformation

Temporary deformation where a material rebounds to its original size and shape when stress is removed, provided its elastic limit is not exceeded.

Plastic (Ductile) Deformation

Permanent stretching or alteration of shape and size occurring when stress exceeds a material's elastic limit without breaking.

Rupture

The breaking or failure of brittle material under stress, typical under near-surface temperature and pressure conditions.

Schist

A foliated metamorphic rock often formed from shale.

Gneiss

A foliated metamorphic rock often formed by the metamorphosis of granite.