Transcript Minerals ppt

Minerals
EQ:
How are minerals a part of rocks?
Of the almost 4000 known minerals,
only about 30 are common.
The most common are quartz, feldspar,
mica, and calcite.
What is a Mineral?
 DEF: A naturally occurring,
inorganic solid that has a
crystal structure & a definite
chemical composition.
 Example: Quartz
Naturally-occurring
 Never man-made
 Ex: Like rocks
Inorganic:
 Means the mineral cannot come
from things that were once living
 Non Example: Coal – it is organic
because it comes from plants that
lived millions of years ago.
Solid
 Definite shape, definite
volume
 A 3-D geometric figure
 Not a liquid or a gas!
Crystal:
 The repeating pattern of
particles, line up when they
form
 Like a snowflake pattern or
rock candy
6 Different Crystal Systems:
 Cubic
Ex: Magnetite
 Hexagonal
Ex: Quartz
 Tetragonal
Ex: Rutile
 Orthorhombic Ex: Sulfur
 Monoclinic
 Triclinic
Ex: Azurite
Ex: Microcline Feldspar
Definite Chemical Composition
 Certain elements form together in
specific ways
 Like Hydrogen & Oxygen (H2O) and
Carbon & Oxygen (CO2) form
together to make these compounds
Physical Properties Identify
Minerals
 Physical Properties include
several “tests” you can perform
on minerals to determine what
type of mineral they might be.
1. Streak Test
 The color of the mineral’s powder
that’s left behind when it is
rubbed across a rough surface
 Example: Pyrite looks like gold
but, it’s streak looks greenishblack
(aka “fool’s gold”)
2. Luster
 Describes how light is reflected from
the mineral’s surface. What does it look
like?
Types of Luster
 Metallic
Ex: Galena
 Glassy
Ex: Topaz
 Waxy, Greasy, Pearly
Ex: Talc
 Dull
Ex: Graphite
 Silky
Ex: Malachite
 Earthy
Ex: Hematite
3. Density
 It’s a calculation

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
(math problem!)
Use a balance to find the mass
Place the mineral in H2O to find the
amount of water it displaces. This
amount is the volume of the mineral.
To find the density, divide mass by
volume
Ex: Sample of Olivine
 Mass = 237 g Volume = 72 cm3
 Density = 237 g/ 72 cm3 = 3.3 g/cm3
4. Cleavage
 One way minerals
break
 Easily split along
flat surfaces
 Ex: Mica & Feldspar
5. Fracture
 One way minerals break
 Break unevenly in irregular ways
 Chipped
 Shell-like
Ex: Quartz
 Jagged points
Ex: Copper & Iron
 Crumbles
Ex: Clay
6. Mohs Hardness Scale
 A scale that ranks 10 minerals from softest to
hardest. You can compare unknown minerals
to the minerals on this scale
 Hardness can be tested by a Scratch Test
 A mineral can scratch any other softer mineral
 It can also BE scratched by any harder mineral
 Softest Mineral – Talc
 Hardest Mineral - Diamond
Color is the most easily observed mineral
property and the least useful!
Some exceptions to the color rule would be
cinnabar, which is always red, and
malachite, which is green.
Many minerals have a similar color.
For example, pure quartz is
colorless or white, impurities can
make the mineral rose, purple or
pink!
Magnetic
Malleable
Radioactive
Flourescence
Taste
Minerals that can be hammered thin or
shaped are said to show these
properties.
Can you think of a mineral that might
be shaped or hammered?
GOLD
Some minerals that
contain Iron, are
magnetic and can
be picked up by a
magnet.
This is the state of
glowing while under
a ultraviolet light.
Some minerals even
glow once the light
is turned off!
Some minerals, such
as this uraninite, are
radioactive.
They give off
subatomic particles
that will activate a
Geiger counter.
Halite (rock salt)
can be identified
by its taste.
This practice is not
recommended!
Discuss the following!
How many of the characteristics
of minerals can you name?
Luster, color, streak, malleable, cleavage/fracture,
taste, fluoresence, magnetic, hardness, and density
Why isn’t color a very good
property to identify most
minerals?
Some minerals have similar colors
Discuss the following!
There are four common minerals,
how many can you name?
quartz,feldspar,mica, and calcite
Of the four common minerals, which
one makes up over 60% of the
Earth’s crust? feldspar
Discuss the following!
Does this mineral show cleavage or
fracture?
Cleveage
Of the four most common minerals,
which is the highest hardness?
quartz
How Earth’s surface forms
 Minerals make rocks
 EX: Granite may be made of many different
minerals (feldspar, mica, hornblende, quartz)
 Rocks are classified by how they are formed
 EX: Igneous rocks form from magma/lava cooling
 d. Different processes change rock & the surface of
the Earth
 EX: Weathering & Erosion break down rocks &
move them to new places