UGA GEOL 3010L Lab Exam

Comprehensive from the study guide of TA Taran

Mineral

A naturally occurring, inorganic crystalline solid with a highly ordered atomic arrangement and a definite (but not necessarily fixed), homogenous chemical composition.

Mineraloid

a naturally occurring, mineral-like substance that does not have a crystalline structure, examples include obsidian, fulgurite, opal, and industrial slag.

Cleavage

is the tendency of a mineral to break along parallel planes

Color

The physical color of a mineral as observed as a reflection of visible light.

Crystal Habit

the general shape of a mineral, including irregularities due to growth. Includes many categories, such as massive, granular, compact, lamellar, platy, prismatic, acicular, bladed fibrous, dendritic, radiating, botryoidal, globular, and more.

Density

refers to the specific gravity of a mineral, which is the weight of a pure mineral in air divided by its weight in air minus its weight in water. Can be approximated by the feel of its heft in your hands and is a measure of the density of the elements in the mineral.

Fracture

The breakage of minerals that don’t cleave or part along any planes. It is broken down into several types, such as conchoidal, splintery, hackly or uneven.

Hardness

is the resistance of a smooth surface on a mineral to scratching.

Luster

Refers to the general appearance of a mineral surface in reflected light.

Streak

the color of the finely powdered mineral on an unglazed piece of white porcelain, called a streak plate. Many minerals streak cannot be measured as they are harder than the streak plate and some produce a streak with no color, many with just a white color.

Miller Indices

representative of a defined plane within a mineral

Cleavage vs Miller Indices

Cleavage is the breakage along the defined plane represented by a Miller index.

How are crystal growth faces/planes different from cleavage plans?

Cleavage planes are planes of breakage in a mineral while growth planes are simply the smooth faces of a formed crystal.

What is an XRD and how does it work?

XRD stands for x-ray diffraction and works by shining a beam of X-rays at a crystalline material and measuring the angles and intensities at which the X-rays bounce off, or scatter, from the atoms

What is EDS and how does it work?

EDS stands for energy dispersive x-ray spectroscopy and works by bombarding a sample with high-energy electrons (usually inside an electron microscope) to eject inner-shell electrons and measuring the unique X-rays emitted as outer-shell electrons fill the resulting vacancies

Carbonates

Mineral group consisting of cations bonded to anionic carbonate (CO₃)^2-, common examples include calcite, aragonite, dolomite, malachite, and azurite.

Halides

formed when halogen anions like F, Cl, Br, or I bond with metal cations, common examples include halite, fluorite, or cryolite.

Native Elements

Elemental minerals consisting of only one element, common examples include diamond, gold, silver, and sulfur.

Oxides

mineral group consisting of a metal cation bonded to (O)^2-, common examples include Cuprite, rutile, hematite, and corundum. Notably, the formula for these minerals can include up to 6 oxygens bonded at once. Hydroxides are not included here.

Phosphates

consisting of cation(s) bonded to (PO₄)^3-, many species exist but most are rare, examples include apatite, vanadinite, turquoise, and wavellite.

Sulfates

mineral group consisting of cations bonded to anionic sulfate (SO₄)^2-, common examples include barite, gypsum, and anhydrite.

Sulfides

consist of mostly metal cations bonded to elemental sulfur, common examples include pyrite, galena, cinnabar, and sphalerite.

Calcite

carbonate mineral with a formula of CaCO₃

Galena

Sulfide mineral with a formula of PbS

Gypsum

sulfate mineral with a formula of CaSO₄ • 2H₂O

Halite

Halide mineral with a formula of NaCl

Hematite

Oxide mineral with a formula of Fe₂O₃

Kaolinite

is a phyllosilicate with a formula of Al₂Si₂O₅(OH)₄

K-feldspar

a tectosilicate mineral (technically group) with the formula KAlSi₃O

Magnetite

oxide mineral with a formula of Fe₃O₄

Molybdenite

sulfide mineral with a formula of MoS₂

Orpiment

sulfide mineral with a formula of As₂S₃

Pyrite

sulfide mineral with a formula of FeS₂

Realgar

sulfide mineral with a formula of AsS

Quartz

a tectosilicate with a formula of SiO₂

Cyclosilicates

a type of silicate mineral characterized by rings of linked tetrahedra, sharing oxygen atoms with a general silicon-to-oxygen ratio of 1:3, common examples include emerald, aquamarine, and tourmaline

Inosilicates

silicate group of infinitely chained SIO₄ tetrahedra, including single and double chain examples with the single having a ratio of 1:3 Si to O, and double having a ratio of 4:11 Si to O. Single chained examples are pyroxenes and double are amphiboles. Common examples include enstatite, augite, hornblende, and tremolite.

Nesosilicates

is a silicate mineral that features independent, isolated \([\text{SiO}_4]^{4-}\) tetrahedra bound together entirely by interstitial metal cations rather than shared oxygen atoms, common examples include the Olivine and Garnet groups, as well as Zircon.

Phyllosilicates

a major class of minerals characterized by parallel sheets of interconnected silicon-oxygen tetrahedra, common examples include muscovite, kaolinite, and serpentine

Sorosilicates

a group of silicate minerals featuring isolated double-tetrahedra building blocks that share a single oxygen atom, common examples include epidote, vesuvianite, and lawsonite

Tectosilicates

a major mineral group defined by a three-dimensional lattice where every oxygen atom in each silicate tetrahedron is shared with neighboring tetrahedra, yielding a 1:2 silicon-to-oxygen ratio, common examples include quartz, the feldspars, and feldspathoids.

Polymorph

A substance with the same formula but different structures, examples include calcite/aragonite, diamond/graphite, the serpentine group, so antigorite, lizardite, and chrysotile.

What causes color variation in minerals?

In garnet, the cations get substituted, causing color changes, such as more calcium in grossular garnet and more iron in almandine garnet.