Download Chapter 4 Minerals

Chapter 4 Minerals
Page 86 in your text book and page
31 in the review book
Mineral: a naturally occurring, inorganic solid with a
specific chemical composition and a definite
crystalline structure.
Inorganic: Are not alive,
nor were ever alive during
any part of their existence.
Solids: Definite shape and definite volume
Some minerals are elements like sulfur or copper but
most are compounds like quartz.
Crystal: A solid in which the atoms are arranged in
repeating patterns.
The longer the crystal
has to grow, the larger
it can get.
The deeper in the ground
the magma is, the
Warmer it is, therefore the slower the
cooling rate and the larger the
crystal.
Magma: Is molten rock beneath the Earth’s surface
Crystals have 6 basic crystal systems (structures)
These are: Cubic,
tetragonal, hexagonal,
Orthorhombic,
Monoclinic and Triclinic.
The following slides are
examples of these six
systems and a mineral
for each one.
This is an example of a cubic crystal such as pyrite.
This is an example of Wulfenite with a tetragonal
shape. The Wulfenite is the yellow mineral.
Here is Pyromorphite and the hexagonal shaped
crystal.
Here is Topaz with the Orthorhombic crystal shape.
This is gypsum with the Monoclinic shape.
Last but not least is Feldspar and it’s triclinic shape.
The two main ways in which minerals form.
1) From the cooling of magma
2) From a mineral saturated solution
There are 3000 minerals.
There are four groups I want you to know.
The Native elements, Silicates, Carbonates, and Oxides.
The native elements: are simply composed of one
element such as Copper and Sulfur and are not
compounds.
The Silicate group: Are made up of Oxygen and
Silicon, the two most abundant elements in the Earth’s
crust.
It is no wonder then that they make up 96% of Earth’s
elements. Quartz and Feldspar are two examples.
The Silicate group: Are made up of Oxygen and
Silicon, the two most abundant elements in the Earth’s
crust.
It is no wonder then that they make up 96% of Earth’s
minerals. Quartz and Feldspar are two examples.
The shape that they form is called the silica
tetrahedron. Oxygen is on the
outside and silicon is on the
inside
This structure can be either a single chain, double
chain or a sheet (page 82 in text).
The next group is called the Carbonates.
Carbonates are minerals composed of one or more
metallic elements with the carbonate compound
CO3
Examples are calcite and dolomite often found in
limestone or marble.
These are basically the only important non silicate
rock forming minerals.
Oxides are compounds of oxygen and a metal.
Examples are hematite (red streak) and magnetite.
Section 4.2 Identifying minerals page 84
Color: The least useful because many minerals have
more than one color and many minerals share the
same color.
Luster: The way that a mineral reflects light. Your
choices are metallic or nonmetallic.
Texture: How a
mineral feels
to the touch. Talc
feels greasy and
olivine feels
granular or “grainy.”
Streak: The powdered and non-weathered color of
the mineral.
Hardness: A minerals resistance to being
scratched.
Moh’s hardness scale 1-10
One (Talc) Is the softest and 10 (Diamond) is the
hardest.
Cleavage Vs Fracture
Cleavage: When a mineral splits relatively easily
along one or more flat planes and has either layers
or multiple flat surfaces or a geometric shape.
Fracture: When a mineral breaks unevenly due to
tightly bonded atoms and have with rough or jagged
edges.
Specific gravity: The ratio of weight of a substance to
the weight of an equal volume of water at 4 degrees
Celsius.
For your lab simply put whether it feels light, medium
or heavy for its size.
Special properties: Often a mineral will have some
unusual characteristic. It may fizz in acid like calcite,
smell like sulfur or glow under UV lights such as these
minerals showing fluorescence.
Chapter 4 Quiz
1. Describe why sugar is not a mineral.
2. List the two main ways that minerals can form.
3. What is the name of the atomic structure of the silicates
and what is the composition of quartz?
4. Why is color the least useful property for identifying
minerals?
5. How do you test a minerals hardness?
Bonus: How can you tell the difference between the Calcite
and Halite?