Topic 1: Solid Earth Materials

Mineral

A substance that is naturally occurring (not made by people), inorganic, solid at normal temperatures, has a definite chemical composition, and an ordered internal structure

Family

Groups of minerals related by composition (eg. sulfides)

Group

Minerals with similar atomic structure (eg. garnet [A3B2(SiO4)3] which includes pyrope, almandine, etc.)

Series

Same structure but different composition Same structure but different composition (eg. olivine series is a continuous chemical variation between two species (solid solution): Mg2SiO4 (forsterite) and Fe2SiO4 (fayalite)

Species

Classically what we refer to as a “mineral” by its name

Polymorph

Same formula but different atomic structure (eg. low and high quartz)

Variety

Same mineral but distinctive physical property (eg. amethyst and rose quartz)

Native Elements

Minerals naturally composed of only one element, eg. diamonds

Silicates

Huge family of minerals that all contain some variant of SiO2 (eg. quartz)

Carbonates

Minerals containing CO3 2- anions (eg. calcite)

Oxides

Contains O 2- anions

Sulfides

Contains sulfur anions

Sulfates

Contains some variation of SO4 2- anions

Silicate Anion

SiO4, Si and O pack together to form a tetrahedron shape

Orthosilicates/Nesosilicates

Isolated tetrahedra with Si:O of 1:4, eg. olivine

Sorosilicates

2 tetrahedra linked by bridging oxygen: Si2O7 6- with Si:O 1:3.5, eg. hemimorphite

Cyclosilicates

Rings where tetrahedra have two bridging oxygens (BO): Si6O18 12- with Si:O of 1:3, eg. beryl

Inosilicates

Single chains where tetrahedra have 2 BO, formula of (SiO3)n 2n-, Si:O of 1:3 (n = infinitely repeating), eg. pyroxene

Double-Chain Inosilicates

Double chains where half the tetrahedral have 2 BO and 2 NBO and the other one has 3 BO and 1 NBO, (Si4O11)n 6n-, Si:O of 1:3, eg. anthophyllite

Phyllosilicates

Infinite sheets have 3 BO and 1 NBO, (Si2O5)n 2n-, Si:O of 1:2.5, eg. micas (sheets!)

Tectosilicates

3D networks where all corners are shared with 4 BO SiO2 with Si:O of 1:2, eg. quartz

Crystal

A crystal is a mineral, or another crystalline chemical compound (i.e. a solid with a specific chemical composition) with an external shape bounded by smooth plane surfaces

Euhedral

“Perfect,” describes a crystal (or mineral grain) what an excellent crystal shape, all the sides pretty much show a nice crystalline structure, eg. very nice-looking quartz crystal

Anhedral

Describes a crystal (or mineral grain) that lacks well-formed crystal faces (at least on the external faces, but the internal atomic arrangement same as the euhedral because… crystal), eg. sand grain

Subhedral

Describes a crystal 9or mineral grain) that are partly bound by good crystal faces, as well as faces that may have been crowded by adjacent mineral grains

Rocks

Any solid mass of mineral(s) or mineral-like matter that occurs naturally

Igneous

Formed through the cooling and solidification of magma or lava and mostly form homogeneous massive bodies, appear crystalline or glassy (crystal size depends on the rate of cooling)

Intrusive Igneous

Formed if it cools underground

Extrusive Igneous

Formed from lava on the surface

Sedimentary

Formed by the deposition and subsequent cementation of minerals or mineral-like substances and tend to be layered and some appear to be rocks composed of smaller pieces of rock cemented together

Metamorphic

Formed from the transformation of existing rock types when subjected to high heat (>150–200 C) and pressure (>100 MPa), and have evidence of recrystallization of foliation (have sort of a banded and folded texture)

Vein

Fractures in rock that can contain crystals

Vug

Irregular cavities in rocks