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23 terms

Chapter 4

Lab
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rock
any coherent, naturally occurring, substance generally composed of minerals
rock cycle
any rock type can become any other rock type
three rock types
igneous, sedimentary, and metamorphic
common non-rocks
beach sand, molten lava, concrete
mineral
a substance that is naturally occurring, inorganic, has a definite chemical composition, is a crystalline
tools for the identification of minerals
hardness, luster, color, streak, cleavage, fracture, cleavage vs. crystal form, and other miscellaneous properties
hardness
measure of the resistance of a mineral to scratching (non breakage)
Mohs Hardness Scale
softness = 1 and hardness = 10
hardness of a ceramic tile
between 5 and 6
streak
the color of the powdery residue of a mineral left behind when it is dragged across an unglazed porcelain plate (hardness of porcelain plate = 6); streak is the same color regardless of the presence or absence of impurities on a mineral
color
streak provides the intrinsic color of a mineral; color is a poor identifier (sulfur is normally yellow and pyrite is normally brassy)
luster
the way a mineral reflects light
metallic
looks like a metal such as gold, silver, iron etc.
non-metallic
vitreous, pearly, resinous (glazed), earthy
cleavage
breakage of a mineral along a flat plane of weakness
fracture
uneven (non-planar) breakage
conchoidal fracture
obsidian or quartz; breaks along a surface marked by concentric circles
splintery fracture
like splinter in a wood
uneven
a catch-all term for non-diagnostic; non-planar breakage
crystal form
how a mineral grows; of a crystal grows out of an apparent flat cleavage face, the face isn't cleavage - it is crystal form
mineral classification: metals
combined with oxygen = oxide minerals; combined with sulfur = sulfide minerals; not combined with other elements = native (native gold, native copper, etc.)
mineral classification: silicates
Si is an important ingredient
ferromagnesian
(Fe and Mg); dark and dense