(Ch. 3) - Minerals

True Mineral

A naturally occurring, inorganic, a solid crystalline substance, have a defined chemical composition, and possess a crystalline internal structure.

Structure of Atoms

Atoms are composed of a nucleus with protons and neutrons, and electrons that orbit the nucleus in shells.

True Mineral

A naturally occurring, inorganic, a solid crystalline substance, have a defined chemical composition, and possess a crystalline internal structure.

Structure of Atoms

Atoms are composed of a nucleus with protons and neutrons, and electrons that orbit the nucleus in shells.

Protons

Positively charged particles with a charge of +1.

Neutrons

Neutral particles with a charge of 0.

Electrons

Negatively charged particles with a charge of -1.

Cation

An atom that loses electrons, gaining a positive charge.

Anion

An atom that gains electrons, gaining a negative charge.

Covalent Bonding

A strong bond formed by sharing electrons, exemplified by diamond.

Ionic Bonding

A moderate bond formed by the transfer of electrons, exemplified by halite (NaCl).

Metallic Bonding

A weak bond where electrons move freely among atoms, exemplified by copper.

Intermolecular Forces (Van der Waals)

The weakest bond, formed by attractions between molecules, exemplified by mica sheets.

Euhedral Mineral

A mineral that had room to grow uninhibited and developed well-defined crystal faces.

Crystallization from a Melt

Minerals form as magma or lava cools, resulting in igneous rocks.

Precipitation from a Solution

Minerals crystallize when a solution becomes oversaturated or evaporates, exemplified by halite.

Precipitation by Organisms

Organisms extract elements to form minerals, exemplified by calcite in shells.

Solid-State Solution

High heat and pressure cause atoms to rearrange into new minerals, resulting in metamorphic rocks.

Most Abundant Elements in Earth's Crust

Oxygen (O), Silicon (Si), Aluminum (Al), Iron (Fe), Calcium (Ca), Sodium (Na), Potassium (K), and Magnesium (Mg).

Color

A common physical property used to identify minerals.

Luster

Describes how a mineral reflects light.

Streak

The color of the mineral's powder.

Hardness

A property that measures a mineral's resistance to scratching.

Cleavage

Describes how a mineral breaks along planes of weakness.

Fracture

Describes how a mineral breaks irregularly if it lacks cleavage.

Density

A property that measures the mass per unit volume of a mineral.

Effervescence (Acid Test)

Indicates that a mineral fizzes in acid, suggesting it contains carbonate, exemplified by calcite.

Magnetism

Indicates that a mineral attracts a magnet, suggesting it contains iron, exemplified by magnetite.

Fluorescence

The property of some minerals to glow under UV light.

Specific Gravity (Heft Test)

A property where some minerals feel much heavier than others of similar size.

One Cleavage Plane

Breaks into sheets (e.g., mica).

Two Cleavage Planes

Can break perpendicular (90°) or non-perpendicular (e.g., feldspar).

Three Cleavage Planes

Can form cubes (perpendicular) or rhombohedral shapes (non-perpendicular).

Without Cleavage

Fractures irregularly or conchoidally (e.g., quartz).

Silicates

Contain silicon-oxygen tetrahedra (e.g., quartz, feldspar).

Carbonates

Contain carbonate ions (e.g., calcite - CaCO3).

Oxides

Metal bonded to oxygen (e.g., hematite - Fe2O3).

Sulfides

Metal bonded to sulfur (e.g., pyrite - FeS2).

Halides

Metal bonded to a halogen (e.g., halite - NaCl).

Sulfates

Contain sulfate ions (e.g., gypsum - CaSO4·2H2O).

Phosphates

Contain phosphate ions.

Native Elements

Pure elements (e.g., gold, copper).

Most Common Rock-Forming Mineral Group

Silicates, because they contain oxygen and silicon, which are the two most abundant elements in Earth's crust.

Olivine

Dark ferromagnesian silicate.

Pyroxene

Dark ferromagnesian silicate.

Amphibole

Dark ferromagnesian silicate.

Micas (Biotite, Muscovite)

Sheet silicates.

Feldspars (Orthoclase, Plagioclase)

Framework silicates.

Quartz

Framework silicate.

Silica Tetrahedron

A basic building block of silicate minerals, consisting of one silicon atom bonded to four oxygen atoms.

Internal Atomic Arrangement

The way atoms are structured in a mineral.

Mineraloid

A substance that lacks a crystalline structure (e.g., opal, obsidian).

Euhedral

Well-formed crystal faces due to uninhibited growth.

Anhedral

Lacks crystal faces due to restricted growth.

Mineral Cleavage

The tendency of a mineral to break along flat planes.

Luster

How a mineral reflects light.

Effervescence

Reaction with acid, causing fizzing.

Mineral Streak

The color of a mineral's powdered form.

Crystal Habit

The common shape a mineral forms.

Silicates

Minerals that contain SiO4.

Carbonates

Minerals containing CO3.

Oxides

Minerals where metal bonds with oxygen.

Sulfides

Minerals containing sulfur.

Halides

Minerals containing halogen elements.

Sulfates

Minerals containing SO4.

Sheet Silicate

Silicates that form 2D sheet structures (e.g., micas).

Framework Silicate

Silicates where tetrahedra share all oxygen atoms (e.g., quartz, feldspar).

Dark Ferromagnesian Silicate

Silicates containing iron and magnesium (e.g., olivine, pyroxene, amphibole).