Download Minerals

Earth Materials
Unit 2 Chapters 3-5 in text
Minerals
I. Composition of minerals
a. Most rocks have a number of different
minerals in them.
b.The element oxygen is the most common
element found in the earth’s crust.
c. Silicon is usually found bonded with
oxygen in most minerals.
d.The most common class of minerals
contains the silicates, the basis of which is
the silicon-oxygen tetrahedra.
II. Rock-forming minerals
a. Oxides contain elements, often metals, and
oxygen
b.Sulfides are usually metals and sulfur
c. Calcium Carbonates include calcite
d.Ferrous minerals contain iron (Fe)
III. New York State Minerals
a. garnet-used as abrasives, found in
metamorphic rock in Adirondacks
b.gypsum, a sulfur-bearing rock, found
where ancient seas dried up in
central/western NY
c. Halite and other salts, from deposits left
by evaporating seas
d.Wollastonite, an evaporite.
IV. The 5 properties of all minerals
1.They are all solid
2.All minerals have a basic crystal structure:
orderly internal pattern of units
3.All minerals have a definite chemical
composition, which means that their
elements are always in the same ratio
4.They are inorganic (do not come from
living things or the remains of living
things).
5.They are naturally occurring, not
anthropogenic
V. Mineral Identification
1.Luster- the manner in which the mineral
_shines in reflected light
Metallic luster; if polished, it would
look like silver, gold or black metal.
Opaque, heavy and dark.
Non-metallic luster; anything that does
not look like a metal.
Ex. Pearly, earthy, dull, glassy
2.Specific gravity- compares the density of
the mineral to the density of water.\
3.Hardness- a measure of the minerals
resistance to being scratched.
Moh’s scale of hardness compares
minerals to each other. (talc is 1,
_diamond_ is 10).
4. Cleavage vs. fracture: description of the
mineral’s tendency to break along definite
angles and planes. Very hard to use
without being able to repeatedly break
samples.
cleavage describes clean, patterned breaks,
while fracture indicates a lack of pattern to
the break.
5.Streak- the color of the powdered form of
a mineral, obtained from dragging it along
an unglazed porcelain plate
6.Color- color is not always helpful, because
one mineral may have trace amounts of
metal and other impurities that will change
the color.
7.Other specific tests/indicators such as:
a. sulfur smells
b.calcite (CaCO3) fizzes even in
weak acids
c. magnetite is magnetic
d.iron rusts
e. halite tastes salty
f. flame tests can accurately
identify minerals and elements