Earth and Space Sciences (Praxis II 5440)

Minerals

Naturally occurring, inorganic solids with a definite chemical composition and an orderly internal crystal structure.

Polymorph

Two minerals with the same chemical composition, but a different crystal structure.

Rocks

Aggregates of one or more minerals, and may also contain mineraloids (minerals lacking a crystalline structure) and organic remains.

sedimentary, igneous, and metamorphic

Three types of rock

formation and the minerals they contain

Rocks are classified based on their ____________.

chemical composition

Minerals are classified by their ___________________ and internal crystalline structure.

Geology

The study of the planet Earth as it pertains to the composition, structure, and origin of its rocks.

Petrology

The study of rocks, including their composition, texture, structure, occurrence, mode of formation, and history.

Mineralogy

The study of minerals.

hardness, luster, color, cleavage, streak, form

The 6 main physical properties used to identify minerals

Hardness

The resistance a mineral has to scratches.

Mohn Hardness Scale

Used to rate hardness from 1 to 10.

Color

Often can not be determined definitively as some minerals can be more than one color.

Luster

Determined by reflected light.

Luster

Described as metallic (shiny), sub-metallic (dull), non-metallic (vitreous, like glass), or earthy (like dirt or powder).

Streak

The true color of the specimen across an unglazed porcelain tile.

Fracture or cleavage

How a mineral reacts to stress, such as being struck with a hammer.

Magnetism, a salty taste, or a pungent odor in a streak test

Other properties that can be used to identify rocks and minerals

Sulfides, oxides/hydroxides, halides, carbonates, sulfates, phosphates, and silicates

The 8 classes of minerals

Dominant anion (negatively charged ion) or anionic group

Property the classes used to classify minerals are based on

The 3 main reasons for how minerals are classified

1. Minerals with the same anion have unmistakable resemblances.

2. Minerals with the same anion are often found in the same geologic environment.

3. Minerals can be further separated into group on the basis of internal structure (similar to the naming convention used to identify inorganic compounds in chemistry)

Sedimentary Rocks

Formed by the process of lithification, which involves compaction, the expulsion of liquids from pores, and the cementation of the pre-exiting rock.

Pressure and temperature

The processes responsible for sedimentary rock formation.

layers, fossils

Sedimentary rocks are often formed in ______________ in the presence of water, and may contain organic remains, such as ______________.

Detrital, biogenic, and chemical

3 groups of sedimentary rocks

Texture

Refers to size, shape, and grains of sedimentary rock.

determine how sedimentary rock was created

Texture can be used to ______________.

Composition

Refers to the types of minerals present in the rock.

origin of sedimentary rock, water

The _____________________ refers to the type of _______________ that was involved in its creation.

Marine deposits

Likely involved ocean environments

Continental deposits

Likely involved dry land and lakes

Igneous rock

Is formed from magma, which is molten material originating from beneath the Earth's surface.

Intrusive, plutonic, hypabyssal, extrusive, or volcanic.

Classifications of igneous rock (dependent upon where magma cools)

Extrusive

Magma that solidifies at or near the surface, cools quickly, and usually has a fine grain. Ex: Basalt

Lava

Magma that flows out of Earth's surface

Crystals

Extrusive rock that cools so quickly _____________ do not have time to form. These rocks have a glassy appearance. Ex: Obsidian

Hypabyssal rock

Igneous rock that is formed at medium depths.

Metamorphic rock

Has been changed by great heat and pressure.

Foliated and unfoliated

Classifications of metamorphic rock

Foliation (layering)

Occurs when rock is compressed along one axis during recrystallization. Ex: Schist and shale

Unfoliated (no banding)

Compressed equally from all sides or lack specific minerals. Ex: Marble