Correlations 1 - Mineralogy

Mineral

1. it must be naturally occurring

2. Crystalline Solid

3. Has definite chemical composition

4. Has ordered internal structure

5. Inorganically formed

amorphous

not crystalline, or not apparently crystalline, made up of glass.

biominerals

are inorganic solids produced by a wide variety of organisms to harden and stiffen tissues.

Crystal

a homogenous solid possessing long-range, three dimensional, internal order.

Rock

is an aggregate of minerals. It can be composed of only one kind of mineral

monomineralic

are rocks that are composed of only one mineral.

Ore Minerals

those minerals from which one or more metals may be extracted at a profit.

Industrial Minerals

those minerals which are, themselves, used for one or more industrial purposes such as in the manufacture of electrical and thermal insulators, refractories, ceramics, glass, abrasives, fertilizers, fluxes, cement, and other building materials.

Gems

those minerals which have ornamental value, and which possess the qualities of beauty, durability, rarity, fashionability and portability.

Mineraloids

-are mineral-like materials that lacks a long range crystalline structure.

Mineral variety

A mineral species may have more than one variety which are distinguished by difference in colour, habit (shape), or other properties.

Mineral series

two or more mineral among which there is a range of

chemical compositions.

Mineral group

A set of minerals with the same basic structure but

different composition.

Cubic

a = b = c ;

α = β = γ = 90°

Tetragonal

a = b ≠ c ;

α = β = γ = 90°

Orthorhombic

a ≠ b ≠ c ;

α = β = γ = 90°

Rhombohedral

a = b = c ;

α = β = γ ≠ 90°

Hexagonal

a = b ≠ c ;

α = β = 90°, γ = 120°

Monoclinic

a ≠ b ≠ c ;

α = γ = 90° , β ≠ 120°

Triclinic

a ≠ b ≠ c ;

α ≠ β ≠ γ ≠ 90°

Habit

The common external morphology that a mineral assumes during an unobstructed growth whether in isolated or aggregates of crystals.

Acicular

fine, slender, needle-like crystals

Banded

exhibiting narrow bands of different colors as textures

Capillary

forming very thin threads which resemble hair

Columnar

stout, column-like individuals

Filiform

forming long and thin little columns which resemble wire

Prismatic

somewhat elongated crystals with well developed prism faces

Tabular

crystals somewhat flattened in one direction

Botryoidal

rounded masses somewhat resembling bunches of grapes

Concentric

plates approximately parallel about a common center

Dendritic

separate from a thicker stem into several more slender ones, similar to branches which divide into smaller sheets

Divergent or Radiated

crystal groups radiating from a center

Drusy

surface covered with a layer of small crystals

Fibrous

groups of parallel slender thread-like strands; need not be easily separable

Foliated

Separate easily into plates or leaves

Geode

cavity line with small crystals

Globular

radiating individuals forming small spherical or hemispherical groups

Granular

aggregates of large or small grains

Mammillary

rounded masses similar to the botryoidal form but the protuberances are more flattened

Massive

Compact crystalline aggregates with no regular forms

Micaceous

splitting readily into exceedingly thin plates or sheets

Oolitic

aggregate of small sphere the size of fish roe

Pisolitic

small globular aggregates about the size of peas or in round concretionary grains

Reniform

rounded grape-like or kidney-shaped masses

Reticulated

lattice-like or network arrangement of slender columnar or threads

Saccharoidal

grains having the size of granulated sugar grains

Stalactitic

resembling pendant cylinders or cones

Stellated

radiating individuals forming star-like or circular groups

Luster

Property of a mineral surface which results from the manner it reflects the incident light

Splendent

dazzling luster recognizable even at a considerable distance connected with smooth and generally even surface

Shining

distinctly observed only on closer observation and is generally related to an uneven sample

Weakly shining

feebly appearing luster even within a short distance

Glimmering

when only a feeble light is reflected by some of the minute aggregated parts constituting the surface

Dull

surface does not reflect any light

Metallic luster

bright reflectance of a metallic surface

Nonmetallic luster

duller reflectance observed when most of the light passes into the mineral and only a small portion of the incident light is reflected from the surface

Vitreous or glassy luster

piece of broken glass

Adamantine

brilliant, almost oily

Resinuous or waxy

luster of a piece of resin, greasy luster

Pearly

the luster of mother of pearl

Silky

luster of a skin of silk or a piece of satin

DIAPHANEITY

Relative ability of minerals to allow light to pass through them.

Transparent

when all objects may be distinctly recognized through a large or small pieces of it.

Semitransparent

when a blurred image of the object can be seen through a thin small piece of it.

Translucent

where no object can be perceived through it but light is transmitted only through the edges of a large piece or through a small piece.

Opaque

when no perceptible degree of light is transmitted even

through the thinnest piece.

Refractive Index

ratio of velocity of light in air and its lesser velocity

in the dense medium

Isotropic

-light moves in all directions with equal velocity and thus each isotropic substance has a single refractive index.

Anisotropic

-velocity of light varies with the crystallographic direction and except for special orientations. Two refractive indices can be measured in any crystal section.

Plane polarized

wave motion is constrained to vibrate in a single

plane

Double refraction

light passing through an anisotropic crystal in all but a few special directions, is resolved into two polarized rays vibrating at right angles to each other

Color

The effect produced by the combination of wavelengths of light incident on the surface of the mineral reaching the observer's eyes.

Labradorescence (Schiller Effect)

a play of colors or colored reflections exhibited especially by labradorite and caused by internal structures that selectively reflect only certain colors.

ADULARESCENCE

An optical phenomenon that defines the gem known as "moonstone." It is a soft glow of light that floats just under the surface of a polished gemstone or under the smooth surface of a gem material.

Chromophores

transition elements

- V, Cr, Mn, Fe, Co, Ni, Cu

Play of colors

exhibits internally the various prismatic

colors when the mineral is turned

Pleochroism

appearance of different colors when an crystal is viewed in transmitted light in different directions

Dichroism

two directions have distinct colors

Opalescene

pearly reflection from the interior of a mineral, like the effect of a glass of water to which a few drops of milk have been added.

Iridescence

shows a series of colors due to light undergoing reflective interferences with itself either on the surface or in the interior.

Chatoyancy

band of light moves from side to side as in a

cat's eye

Asterism

six-pointed star, formed by a beam of light at right angles to each set of inclusions

Fluorescence

on exposure to ultraviolet light, a mineral emits visible light

Phosphorescence

some fluorescent minerals will continue to glow after the ultraviolet light has been turned off

Thermoluminescence

some minerals when heated below red heat will

emit visible light

Triboluminescence

some minerals when rubbed or struck with a

hammer will emit light

Photochromism/Tenebrescence

Unique optical property on certain minerals where they change color upon exposure to sunlight and ultraviolet light. In the mineral Hackmanite, where its color will be deeper after exposure to ultraviolet light and then eventually fade.

STREAK

Color of the powder of the mineral

CLEAVAGE

A marked tendency to break or split easily in certain well-defined directions yielding more or less smooth surfaces which are parallel to the crystal faces or possible crystal system.

PARTING

A plane of structural weakness in a mineral

FRACTURE

The appearance of the surface of a mineral when it does not break along cleavage planes.

Scaly

if the surface is not interrupted by many noticeable protuberances but with few small scales

Even

if the surface has no protuberances or very few

indeterminate and mostly flat ones

Conchoidal

if the surface consists of flat rounded protuberances accompanied by circular grooves as in clam shells.

Uneven

if the surface is entirely interrupted by angular large and small protuberances

Hackly

if surface is jagged and with sharp edge

Fibrous

if certain larger parts resembling fibers can be

distinguished on the surface as in wood

Foliated

if surface is made up of parts resembling planes with length and breadth nearly equal (folia)

HARDNESS

resistance that the surface of a mineral offers to scratching

SPECIFIC GRAVITY

A number which expresses the ratio between the weight of the mineral and the weight of an equal volume of water at 4 degrees Celsius.