Download Minerals chpt 2

 Minerals
are naturally occurring,
inorganic solid, with definite
composition, and in an orderly
arrangement of atoms
When atoms are arranged in a pattern that is
repeated over and over again it is called
crystalline
 Minerals have crystalline patterns
 Graphite is arranged in layered patterns.
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Crystals are solid in which atoms are
arranged in orderly repeating patterns
 A crystal system is a group of crystals that
have similar atomic arrangements and thus
similar external patters
 Crystals that have a place to develop show
the crystal patterns like figure 2, if no space
is provided the arrangement is still there but
no place to show it (figure 2)
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Magma is hot molted rock
If it reaches the surface, it is called lava where it can
cool quickly. If it cools quickly, crystals don’t have to
form (obsidian).
As magma cools, either under surface or at surface, the
atoms lose heat, move together to combine into
compounds thus forming specific minerals
When magma cools slowly crystals form that can be
seen (granite)
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When minerals are dissolved in water and
slowly evaporate, crystals form (halite)
 Silicates
are the most common rock
forming groups containing silicon and
oxygen
 Si
and O are most abundant element in
earth’s crust
Color is true for some minerals, not all so
scientists rely on several techniques to identify
minerals
 Hardness: how easily a mineral can be
scratched according to Mohs Scale (finger
nail, penny, nail, glass)) table 1
 Luster: the way light reflects off a mineral
(metallic and non metallic)
 Specific Gravity (how heavy a mineral is in
relation to water 1 g/cm3
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Streak: rubbed against a un-porcelain plate it
leaves a particular color
 Cleavage and fracture: Minerals break
along smooth flat surfaces have cleavage
(mica)
 Those minerals that break with uneven jagged
edges have fracture
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