Download Metallic minerals

Unit: Earth Materials
Minerals
Albite is a mineral
because it meets 5
important conditions,
as do....
crystals
almandine
apatite
andalusite
augite
azurite
I. There are over 3000 DIFFERENT minerals
identified in the earth’s crust.
1. Few dozen are common (page 16 ESRT)
2. Same minerals found in most rocks.
3. Most minerals are SILICATES:
Oxygen MOST ABUNDANT element in crust
Silicon is usually found with oxygen in most
minerals.
• 4.Rock-forming minerals
• a.Silicates make up the greatest number of
minerals found in rocks
– feldspars are the most common type of
silicate
– quartz is very common in many disguises
Salt River Cobbles
• b.Oxides contain elements, often metals,
and oxygen
• c.Sulfides are usually metals and sulfur
• d.Calcium Carbonates include calcite
• e.Ferrous minerals contain iron (Fe)
Just a few forms of Quartz
A few silicates
5. New York State minerals
• Garnets-used as abrasives, found in
metamorphic rock in Adirondacks
• Gypsum, found where ancient seas
dried up in central/western NY
• Halite and other salts, from deposits
left by evaporating seas
• Wollastonite, shown, an evaporite.
6. Gems are valued because of their beauty,
crystal structure, rarity and durability.
Many gems are actually silicates that have a
unique combination of impurities, creating color,
and internal arrangement of atoms, giving them
a particular luster, hardness and crystal structure.
Semi-precious gems, such as amethyst and
tiger’s eye, are more common.
II. The 5 properties of all
minerals
• The properties of minerals are due to the
internal arrangement of molecules.
1. They are all solid.
2. Crystal Structure: or orderly
internal pattern of units.
3. 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 natural, not
anthropogenic.(not man-made)
III. Mineral Identification:
tests to determine the mineral
1. Luster- the manner in
which the mineral
shines in reflected light.
a. Metallic luster; the
mineral looks like a
metal
b. Non-metallic luster;
anything that does not
look like a metal.
Ex. Pearly, earthy, dull,
• 2. Specific gravitycompares the weight
of the mineral in air
to the weight of the
mineral in water.
• Or, 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.
• cleavage: clean break.
predictable angle and flat
surfaces.
• Fracture: rough and
unpredictable break.
5. Streak- the color of the powdered form of a
mineral, obtained from dragging it along an
unglazed porcelain plate.
• Metallic minerals have
colored streaks.
• Non-metallic tend to
leave white or light.
• Hard minerals leave
no streak.
6. Color- color is not always helpful
• One mineral may
have many
colors,(calcite)
• Many minerals may
have the same color
(white, grey, brown).
• Some are distinct:
• (malachite, azurite)
7. Other specific tests/indicators such as:
• Acid test: calcite fizzes in
even weak HCl acid.
• And calcite shows refraction
• Iron rusts
• magnetism:
• fluorescence
• Flame tests
• Salty taste
8. Crystal shape: how the axes and faces meet
(need equipment and knowledge to do this
properly)
• 6 basic systems:
Clockwise from top right
Wolfenite, olivine, turquoise,
labradorite, siderite, gypsum,
pyrite, uranite
Clockwise from top right
calcite, lapis lazuli, magnetite
ferrous mineral, titanite,
halite, hematite, polarized view
gypum