minerals 2-2

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Transcript minerals 2-2

Unit 2 lesson 2
Minerals of the Earth’s Crust
I. What is a mineral?
A. Structure
1. Mineral= naturally formed,
inorganic solid that has a
definite crystalline structure
2. Elements= pure substances
that cannot be broken down
into simpler substances
 92 naturally occurring
 Ex: gold only has gold atomsnothing else
B. Atoms and Compounds
1. Atoms have 3 particles
 Protons (+) positive
 Neutrons (0) neutral
 Electrons (-) negative
2. Compound= substance made
of two or more elements
chemically joined
 Ex: NaCl Halite or salt
3. Gold and silver are native
elements= minerals
composed of just 1 element
III. The formation, mining, & use of minerals
A. Formation
1. Evaporation= water
will change into gas
leaving the minerals
 gypsum & halite
2. Metamorphic rocks=
changes in pressure
& temp alters rock
 Calcite, garnet, mica,
3. Limestone= surface &
ground water carry
dissolved materials that
crystalize on the floor of
lakes and ponds
 Calcite and dolomite
4. Hot water solutions=
magma heats water which
dissolves metals and
 Gold, copper, pyrite,
5. Pegmatite= mineral
formed by the movement
of magma underground
causing large tear shaped
deposits of minerals
 Topaz
6. Plutons: mineral formed
by the magma rising
upward and slowly
 Feldspar, mica, quartz
B. Mining
1. Ore= a mineral deposit
large enough and pure
enough to be mined for
2. Surface mining: near or at
the surface of the Earth and
used to remove minerals
a. Open pit mine= remove
large, near surface deposits
or economically important
minerals- gold & copper
b. Quarries remove
gravel, building stone,
& crushed rock
c. Surface coal mines
(strip mines) coal is
removed in strips that
can be ½ a mile long
3. Subsurface mining=
mineral deposits are
too deep so
passageways are
dug vertically and
then horizontally
C. Responsible Mining
1. Mine reclamation= process by which land is used for
mining is returned to its original state or better
2. Law since the mid 1970’s
3. Recycling things that contain minerals is also helps to
reduce in the effects of mining
II. Identifying Minerals
A. Color
1. The same mineral can come in several different
2. Color is NOT the best way to identify minerals
B. Luster
1. Luster= the way that a surface reflects light
2. Types of luster
Metallic= bright & reflective
Submetallic= dull, reflective
Silky= fibrous
Resinous= plastic
C. Streak
1. Streak= color of
mineral in powdered
2. Streak plate=
unglazed porcelain
3. Mineral’s streak is
NOT always the same
as it’s color
D. Cleavage and Fracture
1. How the mineral breaks
2. Cleavage= the tendency of some mineral to
break along smooth flat surfaces (chips)
 Mica and halite
3. Fracture= tendency of some minerals to break
unevenly along curved or irregular surfaces
 Halite breaks at 90 degrees
E. Hardness
1. Hardness= mineral’s
resistance to being
2. Hardness scale used
= Moh’s
 1-10
F. Density
1. Density= the amount of how much matter is in a given
amount of space
2. Each mineral will have a specific density that will help to
identify it
G. Special properties
1. optical properties= when minerals are placed
words they will make the word appear double
2. taste= some mineral taste salty (WE WILL NOT
3. magnetism= natural magnet
4. chemical reaction= acid will make the mineral “fizz”
IV. The use of minerals
A. Metallic minerals
1. Have shiny surfaces
2. Do not let light pass through
3. Are good conductors of heat and
4. Can be pounded and stretched
without breaking
5. Used in aircrafts, automobiles,
spacecraft, electronic equipment
& computers
6. Gold, silver & copper
B. Nonmetallic minerals
1. Shiny or dull surfaces
2. May let light pass through
3. Good insulators of
4. Used in concrete,
glassmaking & computer
C. Gemstones
1. Nonmetallic minerals that
are highly valuable for their
beauty rather than
2. Important to be a gemstone
a. color
b. Durability- needs to be able
to be cut
c. Hard enough to be polished
3. Measured in units called