Earth Science: Properties and Classification of Minerals

Flashcards covering definitions, physical properties, crystal structures, and classifications of silicate and non-silicate minerals from the Earth Science lecture.

Mineral

A naturally occurring, inorganic solid that has a definite chemical composition and an orderly, repeating internal crystal structure.

Rock

A naturally occurring solid material that makes up much of Earth's crust, usually consisting of one or more minerals, mineraloids, or other natural materials.

Color

The perceived wavelength of light reflected by a mineral; it is the easiest property to identify but unreliable due to light impurities.

Streak

The color of a mineral in powdered form, which is inherent in almost every mineral and serves as a more diagnostic property than color.

Luster

The behavior of light as it is reflected by the surface of a mineral, categorized broadly into metallic and non-metallic types.

Mohs Hardness Scale

A comparative scale created by Friedrich Mohs that measures a mineral's resistance to scratching, assigning $1$ to Talc (softest) and $10$ to Diamond (hardest).

Cleavage

The tendency of a mineral to break along predictable structural weaknesses, forming smooth, flat surfaces.

Fracture

The texture or shape produced when a mineral breaks into forms other than flat planes, occurring where cleavage is absent.

Specific Gravity

The ratio of the weight of a mineral to the weight of an equal volume of water, where water has a specific gravity of $1$.

Crystal Lattice

A three-dimensional, repeating atomic arrangement of particles (atoms, ions, or molecules) within a crystal structure.

Unit Cell

The smallest repeating portion of a crystal lattice that builds the mineral's overall crystal structure through repetition.

Silicate Minerals

The most abundant mineral group in Earth's crust (making up approximately $90\%$ by volume), containing silicon and oxygen as major components.

Silicate Tetrahedron

The basic structural unit ($SiO_4^{4-}$) of silicate minerals, composed of one central silicon atom surrounded by four oxygen atoms in a tetrahedral shape.

Quartz

A hard, weathering-resistant silicate mineral with the chemical formula $SiO_2$.

Feldspar

The most abundant mineral group in Earth's crust, commonly found in igneous rocks and including orthoclase and plagioclase.

Mica

A silicate mineral group that splits easily into thin, flexible sheets, with common varieties including muscovite and biotite.

Pyroxene

A silicate mineral group common in dark-colored igneous rocks, defined by a single-chain silicate structure.

Amphibole

A silicate mineral group that commonly forms dark, elongated crystals and features a double-chain silicate structure.

Olivine

A silicate mineral common in mafic and ultramafic rocks that is a major constituent of Earth's mantle.

Carbonates

A group of non-silicate minerals containing the carbonate ion ($CO_3^{2-}$), such as calcite ($CaCO_3$) and dolomite.

Oxides

Non-silicate minerals consisting of oxygen combined with one or more other elements, serving as key iron sources (e.g., hematite, $Fe_2O_3$, and magnetite).

Sulfides

Non-silicate minerals containing sulfur combined with a metal, serving as important ore sources for metals like iron, lead, and copper (e.g., pyrite, $FeS_2$, galena, and chalcopyrite).

Sulfates

Non-silicate minerals containing the sulfate ion ($SO_4^{2-}$), such as gypsum and barite.

Halides

Non-silicate minerals containing halogen elements such as chlorine or fluorine, exemplified by halite ($NaCl$).

Native Elements

Minerals that consist of a single uncombined chemical element, such as gold ($Au$), silver ($Ag$), copper ($Cu$), and diamond ($C$).

Rock-forming Minerals

Abundant minerals—primarily silicates along with calcite—that constitute the bulk of Earth's crustal rocks.

Economic Minerals

Minerals extracted for commercial, industrial, or manufacturing value due to their chemical or physical properties.