Minerals EQ: How are minerals a part of rocks?. Of the almost 4000 known minerals, only about 30 are...
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Transcript of Minerals EQ: How are minerals a part of rocks?. Of the almost 4000 known minerals, only about 30 are...
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 Ex: Azurite
Triclinic 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 greenish-black (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
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 – TalcHardest 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!
Malleable
Magnetic
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?
Why isn’t color a very good property to identify most
minerals?
Luster, color, streak, malleable, cleavage/fracture, taste, fluoresence, magnetic, hardness, and density
Some minerals have similar colors
Discuss the following!
There are four common minerals, how many can you
name?
Of the four common minerals, which one makes up over 60%
of the Earth’s crust?
quartz,feldspar,mica, and calcite
feldspar
Discuss the following!
Does this mineral show cleavage or fracture?
Of the four most common minerals, which is the
highest hardness?
Cleveage
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