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MINERALS

MineralsTypical minerals

Copper – Used in electrical wiringGold – Used for jewelryTalc – Baby powderQuartz – The main ingredient in glass

A rock can be defined as an aggregate of two or more minerals, but there are some exceptions.

Earth MineralAn earth mineral is…

Naturally occurringInorganicSolidPossesses an orderly internal structure

Has a definite chemical composition

MINERAL GROUPSRUBY, Garnet, Sapphire, etc.

Mineral GroupsSilicates

Silicone and OxygenNon-silicates

Carbonates Calcite & Dolomite

Oxides Magnetite

Sulfides Bornite

Halides Fluoride

Native Elements Diamond

Silicates

Quartz

Feldspar

Biotite

Hornblende

Oxygen

Silicon

Silicon Tetrahedron- The building block of all Silicates.

Silicate Subgroups

Ferromagnesian(dark)

Non-ferromagnesian(light)

Olivine Light Mica(Muscovite)

Pyroxene group(Augite)

Orthoclase Feldspar

Amphibole group(Hornblende)

Plagioclase Feldspar

Dark Mica(Biotite)

Quartz

Non-silicatesCarbonates

Calcite & Dolomite

Oxides Magnetite

Sulfides Bornite

Halides Fluoride

Native Elements Diamond

PROPERTIESHardness, Cleavage, etc.

Crystal FormExternal expression of a mineral’s orderly

internal arrangement of atoms.Examples

Pyrite – Cubic

Quartz – Hexagonal

LusterThe quality of light reflected from the

surface of a mineral.Examples

Galena - Metallic

Fluorite – Non-metallic

Types of Luster

Metallic The mineral is opaque and reflects light as a metal would.

Submetallic The mineral is opaque and dull. The mineral is dark

Nonmetallic minerals are described using modifiers that refer to commonly known qualities.

Waxy The mineral looks like paraffin or wax.Vitreous The mineral looks like broken glass.Resinous The mineral looks like hardened tree

sap.

ColorUnreliableExample

Quartz

StreakColor of a mineral in its powdered form.Examples

MematiteOolitic

Color - black Steak - black

Sepoular Color - black Steak - black

HardnessThe measure of the resistance of a mineral

to scratching.

Common testing materialsCopper – 3.5Glass – 5.5Fingernail – 2.2

Hardness [Scale]

Mineral Moh’s Scale Rating

Talc 1Gypsum 2Calcite 3Fluorite 4Apatite 5Orthoclase Feldspar 6Quartz 7Topaz 8Corundum 9Diamond 10

CleavageTendency of a mineral to break along

planes of bonding

Fracture describes the quality of the cleavage surface. fibrous ( dull, silky) fracture conchoidal (curved, shell-like lines) fracture irregular (rough, jagged) fracture

Cleavage TypesCubic Cleaves in three directions at 90° to

one anotherRhombohedral Cleaves in three directions

but not at 90° to one anotherOctahedral Cleaves in four directionsDodecahedral Cleaves in six directionsBasal Cleaves in one directionPrismatic Cleaves in two directions

Specific GravitySpecific Gravity of a mineral is a

comparison or ratio of the weight of the mineral to the weight of an equal amount of water. The weight of the equal amount of water is found by finding the difference between the weight of the mineral in air and the weight of the mineral in water.

The most common is 2.5 – 3

OthersTaste

Only soluble minerals have a taste, but it is very important that minerals not be placed in the mouth or on the tongue.

FeelMagnetism

Magnetism is the characteristic that allows a mineral to attract or repel other magnetic materials.

Reaction to Acid