Oh Rockeo, Rockeowhats in a mineral? Identifying and Classifying
Minerals Slide 2 The 7 Ways to Identify a Mineral Color Color
Luster Luster Streak Streak Cleavage/Fracture Cleavage/Fracture
Hardness Density Special Properties Slide 3 Color The same mineral
can exist in several colors due to impurities The same mineral can
exist in several colors due to impurities Sometimes minerals can
even change color when exposed to air or water for some time
Sometimes minerals can even change color when exposed to air or
water for some time ***Not the best way to identify a mineral
***Not the best way to identify a mineral Slide 4 Luster The way a
surface reflects light Is it shiny or dull? Metallic Bright,
reflective Submetallic Dull, reflective Nonmetallic Several types
Slide 5 Streak The color of a mineral in powdered form The color of
a mineral in powdered form Rub the mineral against a streak plate
Rub the mineral against a streak plate Not always the same as the
color Not always the same as the color So, more reliable than color
as a means to identify Slide 6 Cleavage How does it break? Some
minerals have a tendency to break along smooth, flat surfaces These
would have been used for stone tools Slide 7 And Fracture Some
minerals break unevenly along curved or irregular surfaces Some
minerals break unevenly along curved or irregular surfaces Unlike
cleavage which will break at right angles Unlike cleavage which
will break at right angles Slide 8 Hardness A 2 can be scratched by
a fingernail A 2 can be scratched by a fingernail An old penny
scratches at 3.5 An old penny scratches at 3.5 A typical kitchen
knife scratches anything below a 5.5 A typical kitchen knife
scratches anything below a 5.5 Streak plate/steel file at around
6.5 Streak plate/steel file at around 6.5 Resistance to being
scratched Mohs Hardness Scale Talc is a 1 Diamond is a 10 Scratch
the unknown mineral against a reference one A harder mineral will
scratch any soften one Slide 9 Density The measure of how much
matter is in a given amount of space The measure of how much matter
is in a given amount of space Ratio of mass to volume Ratio of mass
to volume Grams per cubic cm Specific Gravity is the ratio of an
objects density to that of water (which has a 1 gram/cubic cm
density Specific Gravity is the ratio of an objects density to that
of water (which has a 1 gram/cubic cm density Iridium is the worlds
most dense, weighing about 22 grams per cubic cm Slide 10 Special
Properties Fluorescent? Does it glow under ultraviolet light?
Taste? Magnetic? Radioactivity? Chemical Reaction? Optical
Properties? Slide 11 Identifying Minerals There are over 3000
minerals we know, so identifying them can be hard There are over
3000 minerals we know, so identifying them can be hard But, even if
we cant positively id them, we can describe them using these
classifications Identifying minerals well takes time, practice, and
a good field guide Identifying minerals well takes time, practice,
and a good field guide
