Transcript Slide 1

Minerals
• Aim: What are minerals?
• Do Now: Minerals are used in
everyday life. List and Describe at
least three examples of minerals
that you think you use in your
everyday life.
I. Mineral Characteristics:
a. Naturally occurring – Forms by
natural geologic processes.
b. Solid substance
c. Orderly crystalline structure – atoms
are arranged in an orderly and
repetitive manner.
Fluorite
d. Definite chemical composition – most
are made up of two or more elements.
e. Generally considered Inorganic – not
living except calcite.
Garnet
II. How do Minerals Form?
4 major processes by which
minerals from:
1. Crystallization
Galena
- As magma cools, elements combine
and harden to form minerals.
- crystallize = to harden
2. Precipitates
- The minerals left behind, or precipitated, out
of a body of water when the water evaporates.
- Like Rock Candy!
Salt Flat - Halite
Limestone Cave
3. Pressure and Temperature
- Minerals form when existing minerals are
subjected to changes in pressure and temp.
(The atoms are rearranged.)
Sulfur
4. Hydrothermal Solutions
- Very hot solutions can cause chemical
reactions with existing minerals to form new
minerals.
Pyrite
Quartz
III. Tetrahedral Crystalline Structure
- Silicon and Oxygen
combine to form
a structure called
the Silicon-Oxygen
Tetrahedron.
- This is found in
Quartz and makes it
the most abundant
mineral
• Aim: What are the properties of
minerals?
• Do Now: How can a scientist tell
the difference between different
minerals? List some of the
properties you would look for to
classify am mineral. Use your
ESRT to help determine useful
properties
• Obtain a beaker of minerals
from the back room.
• Obtain a glass plate and a
streak plate (white plate)
III. Properties of Minerals
1. Color
- Small amounts of different elements
can give the same mineral different
colors.
- Some minerals come in many colors.
Quartz
2. Streak
- Streak is the color of a mineral in its
powdered form.
- Streak is obtained by rubbing a
mineral across a streak plate (a piece of
porcelain.)
3. Luster
- Luster is used to describe how light is
reflected from the surface of a
mineral.
- Metallic
vs.
Non-Metallic
Pyrite
Galena
Sulfur
Feldspar
4. Crystal Form
- Crystal form is the visible expression
of a mineral’s internal arrangement of
atoms.
- Every mineral has a distinct crystal
form.
Calcite
5. Hardness
- Hardness is a measure of the
resistance of a mineral to being
scratched.
- The Mohs scale consists of 10
minerals arranged from
10 (hardest) to 1 (softest).
- Hardness will be determined using a
glass plate.
1. The glass plate should be held
flat on the table.
2. A clean un-scratched surface
should be determined by rubbing
your finger nail on the plate. If
you feel a scratch that spot
should not be sued for the test.
3. The mineral should be scratched
against the glass plate once with
some pressure.
4. If it scratches the glass, then the
mineral is harder
5. If it doesn’t scratch the glass,
then the mineral is softer.
6. Cleavage
- Cleavage is the tendency of a mineral to
cleave, or break, along flat, even
surfaces.
Mica
Calcite
7. Fracture
- Minerals that do now show cleavage
when broken are said to fracture.
- Fracture is the uneven breakage of a
mineral.
Sulfur
Quartz
8. Distinctive Properties of Minerals
- Some minerals can be recognized by
other distinctive properties.
a. HCl (Effervescence - using
Hydrochloric Acid on calcium
carbonate compounds
ex: Calcite.)
b. Magnetic (Hematite)
c. Double Refraction
d. Fluorescence
(Glow in UV light)
****A mineral’s properties depend on the
elements that compose the mineral (its
composition) and its structure (how its
atoms are arranged internally).
Amethyst