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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.
?
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?