Minerals!!What they are, how they form, and how we use ‘em

What are they?A mineral is a naturally occurring, inorganic solid that has a crystal structure and a definite chemical

composition.

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Naturally OccurringThis

NOT this

Inorganic…cannot form from materials that were once part of a living thing…

SolidDefinite volume and shape

Crystal StructuresThe particles of the mineral line up in a pattern that repeats over and

over again

Definite Chemical Composition

= +Quartz

How do we tell them all apart??

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ColorThe color of a mineral can be used to

identify it…

Malachite

Azurite

Gold

Pyrite

…but color is not the most reliable form of identification for most

minerals…

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Color cont’d

StreakThe streak of a mineral is the color of its powder…this is not always the same color as the mineral itself!!!

LusterLuster is the term used to describe

how light is reflected from a mineral’s surface.

Metallic

Waxy

Glassy

Submetallic/dull Earthy

HardnessHow hard a mineral is compared to other minerals, which is determined by a scratch test and rated on Mohs

hardness scale. Fingernail Penny Steel Knife

Window Glass Hard Glass & steel

Everything!

Crystal SystemsMineral’s crystals grow atom by atom in a specific way to form

crystal systems.

Crystal Systems cont’d

CleavageA mineral that splits easily

along a flat surface has cleavage.

FractureA mineral that breaks apart in an irregular way has fracture.

Special Propertiesa.k.a. other cool identifying

features

Fluorescence

Magnetism Chemical

Reactivity

Optical Properties

DensityEach mineral has a characteristic (its own) density. This does not

change…ever!

Density (g/cm3) =Volume (cm3) Mass (g)

Example:

A piece of quartz has a mass of 9 g, and a volume of 3 cm3. What is the density?