Mineralogy and Crystallography Flashcards

Comprehensive vocabulary flashcards covering the branches of mineralogy, crystal systems, symmetry elements, physical properties, rock-forming minerals, and mineral formation processes.

Mineralogy

The scientific field that studies minerals, including their chemistry, crystal structure, physical properties, geological occurrences, and industrial uses.

Crystallography

The branch of mineralogy concerned with the study of the internal and external geometry of crystals.

Physical Mineralogy

The branch of mineralogy focused on the study of the physical properties of minerals.

Chemical Mineralogy

The branch of mineralogy concerned with the study of the chemical structure and properties of minerals.

Agricola

The German physician who wrote several treatises in the mid-1500s summarizing mineral and mining observations that laid the foundation for mineralogy as a science.

Mineral

A naturally occurring, homogeneous solid substance with an ordered atomic structure and a chemical composition representable by a chemical formula.

Silicate Minerals

A major group of minerals that composes over $90\%$ of the Earth's crust.

International Mineralogical Association (IMA)

The organization that has approved over 4,660 of the more than 4,900 known mineral species.

Cubic System

The most symmetrical crystal system where all three crystallographic axes are equal in length and perpendicular to one another.

Halite

A mineral that crystallizes in the cubic system, also known as rock salt, which exhibits brittle tenacity and cleavage in three directions.

Tetragonal System

A crystal system in which two of the three axes are equal in length, and all three axes are perpendicular to one another.

Zircon

A mineral species that belongs to the tetragonal crystal system.

Hexagonal System

A crystal system with four axes where three are equal in length, lie in the same plane, and are separated by equal angles ($120^\circ$), while the fourth axis is perpendicular to them.

Beryl

A mineral example belonging to the hexagonal crystal system, represented in gemstone forms like emerald.

Rhombohedral System

A crystal system where all three axes are equal in length ($a = b = c$), but the angles between them are equal and not equal to $90^\circ$ (\alpha = \beta = \gamma \neq 90^\circ).

Calcite

A rock-forming mineral with formula $CaCO_3$, belonging to the rhombohedral system, which exhibits cleavage in two directions and is widely used in limestone/marble form for cement and concrete.

Orthorhombic System

A crystal system in which all three axes are unequal in length ($a \neq b \neq c$), and all are perpendicular to one another (\alpha = \beta = \gamma = 90^\circ).

Olivine

A rock-forming mineral that crystallizes in the orthorhombic system and is almost always green in color.

Triclinic System

The least symmetrical crystal system, where all three axes are unequal in length ($a \neq b \neq c$) and none are perpendicular to another (\alpha \neq \beta \neq \gamma \neq 90^\circ).

Kyanite

A mineral specimen that belongs to the triclinic crystal system.

Monoclinic System

A crystal system in which all three axes are unequal in length ($a \neq b \neq c$), and two axes are perpendicular to each other (\alpha = \gamma = 90^\circ, \beta \neq 90^\circ).

Gypsum

A mineral with a Mohs hardness of 2 that belongs to the monoclinic crystal system and can display silky luster.

Plane of Symmetry

An imaginary plane passing through the center of a crystal that divides it into two exactly similar halves.

Axis of Symmetry

An imaginary line passing through a crystal's center around which rotation replicates the exact face appearance 'n' times in a $360^\circ$ turn.

Center of Symmetry

A point in a crystal such that an imaginary line drawn from any face, edge, or corner through this point finds an identical feature at an equal distance on the opposite side.

Six-fold Axis

An axis of symmetry where a crystal presents the same appearance 6 times during a full $360^\circ$ rotation (every $60^\circ$).

Tenacity

The physical property describing how a mineral behaves under deformation or stress.

Brittle

A tenacity property where a mineral exhibits a tendency to fracture, break, or powder easily when subjected to force.

Malleable

A tenacity property of minerals (e.g., Gold) that allows them to be hammered or molded into thin sheets without breaking.

Sectile

A tenacity property describing minerals (e.g., Celestite) that can be easily cut into thin shavings with a knife.

Ductile

A tenacity property describing minerals (e.g., Copper) that can be easily drawn into thin wires or stretched without breaking.

Elastic Mineral

A mineral (e.g., Muscovite) capable of bending and returning to its original shape after deformation.

Mohs Hardness Scale

A relative scale ranking mineral scratch resistance from 1 (Talc) to 10 (Diamond).

Cleavage

The tendency of a crystal to split smoothly along structural planes of weakness parallel to atomic layers.

Fracture

The irregular way a mineral breaks when it contains no specific structural planes of weakness.

Conchoidal Fracture

A type of fracture resulting in smooth, curved surfaces resembling the interior of a seashell.

Hackly Fracture

A type of fracture producing jagged, rough edges on brittle minerals subjected to stress.

Streak

The color of a mineral's fine powder produced when scraped across an unglazed porcelain streak plate.

Luster

The general visual appearance of a mineral surface in reflected light, broadly classified as metallic or non-metallic.

Vitreous Luster

A non-metallic luster that gives a reflective appearance similar to glass, as seen in clear quartz and tourmaline.

Adamantine Luster

The highest, most brilliant non-metallic luster observed in minerals, characteristic of diamonds.

Allochromatic

Refers to minerals that can occur in a variety of colors due to impurities, such as Quartz (which can be clear, white, black, pink, blue, or purple).

Specific Gravity

The ratio of the weight of a mineral to the weight of an equal volume of water.

Essential Minerals

Rock-forming minerals that constitute more than $50\%$ of a rock's overall composition.

Accessory Minerals

Minerals that occur in rocks in limited quantities as small crystals, without defining the primary rock type.

Augite

A rock-forming mineral commonly occurring in mafic and intermediate igneous rocks, typically green, black, or brown.

Muscovite

A mica mineral that easily cleaves into thin flat sheets, exhibits elastic tenacity, and serves as an excellent electrical and thermal insulator.

Carbonization

The slow process of conversion of dead vegetation into carbon-dense coal over millions of years.

Coke

A tough, porous, black substance that is an almost pure form of carbon, used in steel manufacturing and metal extraction.

Coal Tar

A thick, black liquid with an unpleasant smell, containing about 200 substances, used as raw material for synthetic dyes, drugs, plastics, and paints.