Earth Science 1st Semester (STEM)

Mineral

Naturally-occurring inorganic substances with a definite chemical composition and physical properties.

Color

The wavelength of light reflected from a mineral’s surface; not always reliable for identification.

Luster

The way light reflects from a mineral's surface; can be metallic or non-metallic.

Hardness

A mineral's ability to resist abrasion or scratching, measured by the Mohs Hardness Scale.

Streak

The color of a mineral in powder form, tested using a streak plate.

Crystal Shape

The outward expression of a mineral’s internal arrangement of atoms.

Fracture

The way a mineral breaks when it does not break along cleavage planes.

Cleavage

When a mineral breaks into flat surfaces along planes of weak bonding.

Specific Gravity

The weight of a mineral compared to an equal volume of water.

Native Elements

Minerals composed of only one element, such as sulfur or gold.

Igneous Rocks

Formed from the cooling and solidification of magma or lava.

Intrusive Rocks

Igneous rocks formed inside the Earth from slow cooling (e.g., granite).

Extrusive Rocks

Igneous rocks formed on the Earth's surface from rapid cooling (e.g., basalt).

Sedimentary Rocks

Formed from the compaction and cementation of sediments.

Clastic Rocks

Sedimentary rocks formed from fragments of other rocks (e.g., sandstone).

Chemical Rocks

Sedimentary rocks formed from the precipitation of minerals (e.g., limestone).

Organic Rocks

Sedimentary rocks formed from the remains of living organisms (e.g., coal).

Metamorphic Rocks

Formed from the transformation of existing rocks under heat and pressure.

Foliated Rocks

Metamorphic rocks with a layered appearance (e.g., schist).

Non-foliated Rocks

Metamorphic rocks without distinct layers (e.g., marble).

Magma

Molten rock beneath the Earth's surface.

Lava

Magma that reaches the Earth's surface.

Lithification

The process of turning sediments into rock through compaction and cementation.

Fossils

Preserved remains or traces of ancient organisms found in sedimentary rocks.

Metamorphism

The process of transforming existing rocks by heat, pressure, and fluids.

Parent Rock (Protolith)

The original rock from which a metamorphic rock forms.

Regional Metamorphism

Metamorphism occurring over large areas under high pressure and temperature.

Contact Metamorphism

Metamorphism occurring when rocks are heated by nearby molten magma.

Texture

The size, shape, and arrangement of crystals in a rock.

Fine-grained Texture

Produced when lava cools quickly, resulting in small crystals.

Coarse-grained Texture

Produced when magma cools slowly, allowing large crystals to form.

Porphyritic Texture

Results from magma with large crystals migrating to a location with increased cooling.

Glassy Texture

Produced by very rapid cooling, resulting in no crystal formation (e.g., obsidian).

Pyroclastic Texture

A rock texture formed from volcanic fragments.

Granitic Rocks

Light-colored igneous rocks composed mainly of quartz and feldspar.

Basaltic Rocks

Dark igneous rocks rich in iron and magnesium (e.g., basalt).

Andesitic Rocks

Intermediate igneous rocks between granitic and basaltic compositions.

Ultramafic Rocks

Igneous rocks containing mostly dark-colored minerals like olivine.

Breccia

A type of sedimentary rock formed from angular fragments.

Shale

A sedimentary rock formed from compacted clay particles.