Cochise College              Phy
These minerals can be identified by their   distinct physical properties. 
Refer to Photos of Minerals for more  visual examples of each of these minerals.
     Muscovite mica is colorless   to a very pale brown in color.  It peels easily into very thin,
flexible,   elastic sheets that are nearly colorless. Muscovite is also known as white   mica.
     Biotite mica ranges from   dark brown to black.  It also peels in very thin, flexible, elastic
sheets   like muscovite mica.  Biotite is also known as black mica.
     Sulfur has a distinctive   bright lemon yellow color.  It may be either transparent or
translucent.  Sulfur has no  cleavage and will break with a conchoidal fracture (shell-like). 
Sulfur is   brittle (breaks easily).  It may also have traces of a sulfury odor.
     Pyrite is also known as "fools gold" because it has a yellow metallic color. Pyrite can
be  distinguished from native gold by several different properties.  Pyrite is   much harder
than  gold; it cannot be scratched by a steel straight pin.  Pyrite is brittle; it can be crushed
to a  powder, whereas gold simply   flattens out because it is a metal.  A streak test can also
distinguish pyrite from gold; pyrite produces a   greenish black streak and gold produces a
yellow streak.
5. magnetite  
     Magnetite is dark brown to   black mineral.  It is easy to identify because it is the only
common mineral   that can be picked up by a magnet.  It produces a black streak. 
     Hematite ranges in color   from a powdery brownish red to black to a metallic black.
A black specimen   of hematite can closely resemble magnetite, but hematite is not
magnet  and   it produces a brownish red streak.  Powdered hematite is used as rouge. 
7. galena
     Galena has a metallic luster   and is gray in color.  Its most outstanding feature is its
high density; a   sample of galena is much heavier than other minerals of the same size. 
Galena is a lead ore.  Galena also has three directions of cleavage at right   angles to
each  other; it breaks into shiny metallic-looking cubes.
8. olivine  
     Olivine is a transparent to   translucent mineral with a distinct yellow green color. 
It often occurs as   clusters of small grains in a dark, fine-grained volcanic rock known as
a  basalt. Olivine grains only rarely get up to pea-sized.  Olivine has not cleavage and
breaks  with a conchoidal fracture.  If the   material is clear and solid enough, it can be
cut and  polished and becomes   the gemstone olivine.
9. azurite
     Azurite is a bright blue   mineral associated with copper ore. It may occur with green
malachite, also   a copper ore.  It is relatively soft at 3.5 on Mohs scale of hardness.
10. malachite
     Malachite is a rich green to   dark green copper mineral.  It can occur on its own or
with  azurite, a   mineral that it is closely related to in chemistry.  It is relatively soft   at
3.5 on Mohs  scale of hardness.
11. talc
     Talc is the softest mineral;   it can be easily scratched with you fingernail. It may
have a  pearly luster.  Talc is often described as having a greasy or soapy feel to it. 
Talc is  commonly white, but can also be a pale green or pale pink. You might get
talc and gypsum confused because they can have similar appearances.
     Gypsum is a soft,   light-colored mineral.  Its color can be colorless and transparent
(selenite)   or white, pale pink or pale brown. If crystallized, it displays one   direction
of  excellent cleavage, but the cleavage fragments are much  thicker than those of
mica and  the fragments are not elastic. Generally, it   lacks the greasy feel of talc.
One form of  gypsum tends to form with a   fibrous structure (satinspar).
13, 14, 15, and 16 are varieties of the mineral quartz. 
     Milky quartz is white   quartz.  The white color comes from carbon dioxide gas
trapped  within the   quartz structure.  Milky quartz is usually massive, but well
well-formed crystals  are also   common.  In the Huachuca mountains, milky quartz
occurs a a filling material   in  fractures (mineral veins). All quartz has a hardness of 7
on Mohs scale   of hardness and  can easily scratch glass. Milky quartz is shiny and
translucent.  Quartz has no cleavage  and breaks with a fracture that ranges   from
conchoidal to irregular.
     Rose quartz is a variety of massive, translucent quartz with a pink color.   It has no
cleavage, it breaks with a conchoidal fracture, and it has a shiny   surface. Depending on
quality, it can be used as a gemstone or a decorative   garden stone.  Two major
occurrences of rose quartz are Maine and the Black   Hills of South Dakota.
15. amethyst
     Amethyst is purple quartz.  It can occur as well-formed quartz crystals in geodes or
deformed crystals   in a mineral vein.  If the quality is high enough, amethyst is used as a
gemstone. The luster of amethyst is usually vitreous (shiny).
16. agate
     Agate is a cryptocrystalline   variety of quartz; this means that the actual fibers of quartz
are so small   that they can barely be seen with a regular microscope.  Agate commonly   forms
as a series of colored bands and rough agate has a dull to waxy   texture.  Agate polishes to a
high gloss and is a semi-precious gemstone.
     Orthoclase feldspar is a   common silicate mineral.  It is responsible for the pink to red
colors found   in the igneous rock, granite.  The most common color of orthoclase is salmon
(pinkish orange), but it may also more rarely be white or a pale   bluish-green (amazonite).
Orthoclase grains are commonly less than one   eighth of an inch. Large, pure pieces of
orthoclase display two directions   of cleavage oriented at right angles to each other.
Orthoclase has a   hardness of 6 on Mohs scale of hardness and therefore can be scratched
by a   piece of quartz.
18. calcite
     Calcite is a very common   mineral. The difficulty in identifying it is that can occur in a
very  large   variety of colors and forms.  One of the most common forms of calcite   crystals
are pointy  pyramids that resemble a dog's canine tooth (dogtoothspar).  Large, pure pieces
of crystalline  calcite display three directions of   cleavage that are inclined  (not at 90 degrees). 
Calcite  ranges from transparent to translucent.  Colors may be colorless, white, cream, pale
yellow,  yellow-brown, brown, and   even red due to impurities.  The easiest way to distinguish
calcite  is with   an acid test; concentrated hydrochloric acid with cause abundant bubbles to
form as it  reacts with the calcite.
     It is sometimes easy to   mistake fluorite for calcite on a quick examination.  However, if
you  pay   careful attention, fluorite has four directions of cleavage compared to   three
directions of  cleavage for calcite. Fluorite is also harder than   calcite (4 on Mohs scale of
hardness) and can  scratch a piece of calcite.  Fluorite is often more colorful than calcite
and can be purple, green,  yellow, pink, brown, or colorless and may even show two or more
colors on   the same specimen.  Fluorite crystals are usually cubes or octahedrons.  Above
all, fluorite does not fizz in contact  with hydrochloric acid.
20. graphite
     Graphite is a very soft,   dark gray mineral with a semi-metallic luster. It has a greasy feel
and  you   can write on a piece of paper with it. It is this last physical property   that is
responsible for  this mineral being used in pencils.