Earth Science - Rocks, Rock Formation, and Minerals

A set of vocabulary flashcards based on the Earth Science lecture notes covering rock-forming minerals, crystal habits, physical properties, cleavage, hardness, and chemical classes.

Mineral

A naturally occurring, inorganic substance that is usually solid, crystalline, and stable at room temperature.

Rock-Forming Minerals

The group of common minerals from which the vast majority of rocks are formed, including feldspars, quartz, amphiboles, micas, olivine, garnet, calcite, and pyroxenes.

Accessory Minerals

Minerals present within a rock in small quantities, such as zircon, monazite, apatite, titanite, tourmaline, and pyrite, which provide valuable geological insights and aid in determining rock age.

Eight Abundant Crustal Elements

The eight elements that make up $98\%$ of the Earth's crust: oxygen, silicon, aluminium, iron, magnesium, calcium, sodium, and potassium.

Andalusite

An aluminium-rich mineral with the chemical formula $\text{Al}_2\text{SiO}_5$ that is unlikely to be found in an aluminium-poor rock such as quartzite.

Euhedral Crystals

Crystals that possess well-developed crystal faces, such as garnet crystals.

Crystal Habit

The characteristic shape of an individual mineral crystal or an aggregate of crystals.

Acicular Habit

A needle-like crystal habit, as exhibited by natrolite and rutile.

Bladed Habit

A blade-like, slender, and flattened crystal habit, as exhibited by kyanite.

Botryoidal Habit

Grape-like mineral masses, as exhibited by hematite and malachite.

Columnar Habit

A long, slender prismatic crystal shape, as exhibited by calcite and gypsum.

Cubic Habit

A cube-shaped crystal habit, as exhibited by pyrite, galena, and halite.

Dendritic Habit

A tree-like crystal habit branching in multiple directions, as exhibited by pyrolusite, native copper, and native silver.

Fibrous Habit

A crystal habit consisting of very slender prisms, as exhibited by asbestos and tremolite.

Foliated Habit

A layered crystal structure that parts easily into very thin sheets, as exhibited by muscovite and biotite.

Granular Habit

Aggregates of crystals without distinct individual faces, as exhibited by bornite and scheelite.

Hexagonal Habit

A six-sided crystal habit, as exhibited by quartz and hanksite.

Massive Habit

A mineral occurrence with no distinct crystal shape, as exhibited by turquoise and realgar.

Octahedral Habit

An eight-sided crystal habit, as exhibited by diamond and magnetite.

Platy Habit

A flat, tablet-shaped crystal habit, as exhibited by wulfenite.

Prismatic Habit

An elongate, prism-like crystal habit, as exhibited by tourmaline and beryl.

Radial Habit

A star-like crystal habit radiating outwards from a central point, as exhibited by wavellite and pyrophyllite.

Mohs Hardness Scale

A relative scale defined by ten indicator minerals ranking scratch resistance from $1$ (talc) to $10$ (diamond).

Mineral Streak

The color of the powdered mineral mark left after being rubbed against unglazed porcelain; applicable only to minerals with a Mohs hardness of $7$ or less.

Hematite Streak

The dark blood-red powdered streak produced by hematite, even though hand samples may appear black, silver, or brown-red.

Lustre

The way the surface of a mineral reflects light, controlled by the types of atoms present and their chemical bonding.

Adamantine Lustre

A brilliant, diamond-like reflection seen in transparent minerals with a high refractive index, such as diamond, cerussite, and cubic zirconia.

Resinous Lustre

A waxy, resin-like surface glow seen in minerals such as fire opal and sulfur.

Vitreous Lustre

A glass-like surface appearance, as exhibited by calcite, quartz, and beryl.

Cleavage

The tendency of a mineral to break along smooth, flat surfaces corresponding to planes of weakness in its crystal structure.

Iceland Spar Cleavage

A variety of calcite that cleaves readily along three planes of weakness into distinctive rhombs.

Conchoidal Fracture

A smooth, curved fracture surface resembling broken glass or a shell, exhibited by minerals without cleavage planes such as quartz.

Bowen's Reaction Series

The predictable sequence in which minerals crystallize from cooling magma, where high-temperature minerals like olivine crystallize first and lower-temperature minerals like quartz crystallize last.

Evaporite Deposits

Mineral deposits formed when evaporating bodies of water concentrate and precipitate dissolved minerals such as halite (rock salt) and gypsum.

Regional Metamorphism

A metamorphic process affecting large areas under intense tectonic pressure and heat, producing foliated rocks such as schist and gneiss.

Contact Metamorphism

A localized metamorphic process occurring when magma intrudes into surrounding rock and bakes adjacent rock with heat, producing hornfels.

Hydrothermal Metamorphism

Metamorphic alteration caused by hot, chemically active fluids interacting with rock to exchange ions through metasomatism.

Specific Gravity

The ratio of a mineral's density to the density of water, useful for distinguishing look-alike minerals like gold ($\approx 19.3$) and pyrite ($\approx 5.0$).

Mineral Chemical Classification

The categorization of minerals into classes based on their dominant chemical anion or anion group.

Silicates

A mineral class defined by the $\text{SiO}_4$ anion group, including quartz, feldspar, mica, and olivine.

Carbonates

A mineral class defined by the $\text{CO}_3$ anion group, including calcite and dolomite.

Halides

A mineral class defined by halogen anions such as $\text{F}^-$ and $\text{Cl}^-$, including halite and fluorite.