The Lithosphere - Minerals, Rocks and Geological Time

Flashcards covering key concepts about minerals, rocks, their properties, structures, and classifications, based on lecture notes.

Geological Definition of a Mineral

Naturally occurring, generally inorganic, solid substance with an orderly crystalline structure and a definite chemical composition that allows for some variation.

Definition of a Rock

A solid mass of minerals or mineral-like matter that occurs naturally, where minerals are joined together in such a way that their individual properties are retained.

Atoms

Smallest particles of matter that cannot be chemically split.

Atomic Number

The number of protons in the nucleus of an atom, which determines the atom’s chemical nature.

Mass Number

The number of protons and neutrons in the nucleus of an atom

Ionic Bonding

Atoms gain or lose outermost electrons to form ions.

Covalent Bonding

Atoms share one or more valence electrons.

Metallic Bonding

Valence electrons are free to migrate among atoms.

Precipitation of Mineral Matter

Ions dissolved in an aqueous solution reach saturation and start forming crystalline solids.

Crystallization of Molten Rock

When the magma is hot, the atoms are mobile, but when the magma cools, the atoms slow and begin to chemically combine, generating a mosaic of intergrown crystals.

Deposition as a Result of Biological Processes

Marine organisms use calcium or silica from seawater and secrete external skeletons composed of calcium carbonate (CaCO3) or silica.

Lustre

Appearance of a mineral in reflected light.

Streak

Color of a mineral in its powdered form, obtained by rubbing mineral across a porcelain streak plate.

Crystal Shape, or Habit

Characteristic shape of a crystal or aggregate of crystals.

Hardness

Resistance of a mineral to abrasion or scratching.

Cleavage

Tendency to break along planes of weak bonding, producing smooth, flat surfaces.

Fracture

Minerals with equally strong bonds have an absence of cleavage, resulting in irregular, conchoidal, splintery, or fibrous fractures.

Tenacity

The mineral’s resistance to breaking or deforming.

Density

Mass per unit volume.

Specific Gravity

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

Crystalline Solid

Any natural solid with orderly, repeating internal structures.

Unit Cells

Atomic arrangement that results in the basic building blocks of a mineral crystal.

Steno’s Law (Law of Constancy of Interfacial Angles)

Regardless of crystal size, the angles between equivalent crystal faces of the same mineral are consistent.

Polymorphs

Minerals with identical composition but different crystalline structures.

Rock-Forming Minerals

Common minerals that make up most of the rocks of Earth’s crust.

Economic Minerals

Minerals used extensively in the manufacture of products.

Mineral Species

Specimens that exhibit similar internal structure and chemical compositions.

Mineral Varieties

Varieties of Mineral Species

Silicate Minerals

The most common type of minerals, accounting for >90% of Earth’s crust.

Nonsilicate Minerals

Minerals that are not as common as the silicates but important economically.

Silicon–oxygen tetrahedron

Fundamental building block of silicate minerals, consisting of four oxygen ions surrounding a much smaller silicon ion.

Polymerization

SiO4 tetrahedra link to one another in a variety of configurations

Independent Tetrahedra

Silicate minerals with independent tetrahedra

Three-Dimensional Framework

Silicate minerals with three-dimensional frameworks

Light (Nonferromagnesian) Silicates

Generally light in color, with a specific gravity of approximately 2.7, containing varying amounts of Al, K, Ca, and Na but lacking Fe and Mg.

Feldspar Group

Most common mineral group, exhibiting two directions of perfect cleavage at 90º.

Quartz

Hard and resistant to weathering, often forming hexagonal crystals, colored by impurities.

Muscovite

Excellent cleavage in one direction, used as glass during the Middle Ages and produces the glimmering brilliance often seen in beach sand.

Dark (Ferromagnesian) Silicates

Contain iron and/or magnesium in their structure, generally dark in color, with a specific gravity between 3.2 and 3.6.

Carbonates

Two most common carbonates are calcite (CaCO3) and dolomite CaMg(CO3)2