Rocks & Minerals

Batholith

large mass of intrusive igneous rock believed to have solidified deep within the earth

Cementation

The process in which minerals precipitate into pore spaces between sediment grains and bind sediments together to form rock.

Contact metamorphism

a change in the texture, structure, or chemical composition of a rock due to contact with magma.

Dike

igneous rock feature formed when magma is squeezed into a vertical crack that cuts across rock layers and hardens underground

Felsic

a type of magma rich in silica that forms light-colored igneous rock; typically the basis of continental crust

Foliated

rocks that have banding or striping due to extreme pressure

Fossil

the remains, impression, or any other evidence of life from another geologic age preserved in rock

Igneous rock

rock formed by the cooling and hardening of magma or lava

Lava

molten rock that reaches Earth's surface

Mafic

type of magma rich in iron and magnesium and low in silica; typically the basis of oceanic crust

Magma

the hot molten rock that forms beneath Earth's surface

Metamorphic rock

rock that has undergone chemical or structural change due to the effects of heat & pressure

Pluton

an intrusion of magma into Earth's crust

Regional metamorphism

the process of rock formation that results from large areas of rocks being under intense heat & pressure of mountain-building movements

Rock

a naturally formed group of minerals bound together

Rock cycle

a repeated series of events by which rock gradually and continually changes between igneous, sedimentary & metamorphic forms

Sediment

solid particles such as weathered rock fragments, plant & animal remains, or minerals that settle out of solution on lake & ocean bottoms

Sedimentary rock

rock formed by the compaction and cementing of layers of sediments

Sill

igneous rock feature formed when magma is squeezed into a horizontal crack between layers of rock and hardens underground

Stratification

the layering of sedimentary rock

Unfoliated

rocks that have no banding or striping due to extreme pressure

Cleavage

the tendency of a mineral to split along planes of its crystalline structure where bonds are weakest; some minerals break only in one direction, others break in two or more directions

Crystal

solid substance in which atoms are arranged in an orderly pattern that repeats over & over again

Density

the ratio between the mass & the volume of a substance

Fracture

the property of a mineral that describes an irregular pattern of breakage in a direction other than along cleavage planes; i.e. when a mineral does not have a definite cleavage pattern

Hardness

the resistance of a mineral to scratching

Inorganic

is not now & has never been living tissue

Luster

the property of a mineral that describes the quality or appearance of light reflected from its surface

Mineral

a naturally-occurring inorganic solid with a distinct chemical composition and crystalline structure

Mineralogy

the study of minerals and their properties

Silicate

any mineral that has it building block a tetrahedron of silicon & oxygen; most common group of minerals

Specific gravity

the ratio of the weight of a substance to the weight of an equal volume of water

Streak

the property of a mineral that describes its color in powdered form

Conchoidal

a type of fracture where it breaks along a curved, ridged surface like the inside of a clam shell

Clastic

Form when fragments of other rocks are compacted and cemented together

Organic

Composed of matter that is alive or was once alive.