| Minerals
A Mineral is a natural,
inorganic solid, with definite structure and composition:
1) Formed by natural processes.
2) Inorganic - not formed by any processes
resulting from living
organisms.
3) Solids.
4) Unique composition of elements or
compounds.
5) Arranged in repeating geometric
patterns called crystals:
[From USGS:
CLICK HERE to see each of the Minerals in this picture
individually]
CLICK
HERE to go to a Volcano World lesson on minerals.
Crystals
Are solids formed by the atoms or
molecules of the mineral being
arranged in repeating geometric
patterns:
[From
another Volcano World Mineral Lesson]
Different substances have different
crystal shapes; they fit into 6 main Crystal Systems:
- Isometric (AKA Cubic),
- Tetragonal,
- Hexagonal (which includes Trigonal),
- Orthorhombic,
- Monoclinic, and
- Triclinic
[Go To The Mineral and Gemstone Kingdom click on Glossary, click on
"C," scroll down to "Crystal system," and click on each of the above terms
in turn to see animated representations of the crystal systems!]
Click HERE to go to Introduction to
Crystallography and Mineral Crystal Systems, Written by Mike Howard - Illustrated
by Darcy Howard:
This is an in-depth study one might expect to find on a University site, but after
a while you find out that "rockhounds" are the geology equivalent of
"amateur" astronomers: the main difference between many of them and the
professionals is that many "amateurs" make their livings doing something else,
and put their passion into their pastime.
HOW MINERALS FORM
Cooling of Magma, or Molten Rock
- type of mineral based on the composition
of the magma.
From Solution
- minerals dissolved in liquid, mostly
water based solutions
- liquids evaporate and mineral crystals
form from left behind minerals
Mineral Groups
Minerals can be organized, mainly according to their
chemistry, into the following classes:
[ List and links from/to: Amethyst Galleries, Inc. Copyright ©1998]
- Elements
Class: The Native Metals and their alloys and the Nonmetals.
- Sulfides
Class: The Sulfides, the Selenides, the Tellurides, the Arsenides, the
Antimonides, the Bismuthinides and the Sulfosalts.
- Halides
Class: The Fluorides, the Chlorides and the Iodides.
- Oxides
Class: The Oxides and the Hydroxides.
- Carbonates
Class: The Carbonates, the Nitrates and the Borates.
- Sulfates
Class: The Sulfates, the Sulfites, the Chromates, the Molybdates, the Selenates,
the Selenites, the Tellurates, the Tellurites and the Tungstates (or the Wolframates).
- Phosphates
Class: The Phosphates, the Arsenates, the Vanadates and the Antimonates.
- Silicates
Class: The Silicates are the largest class, made up
of O and Si, the two most abundant elements in Earth's crust.
- The Organics
Class: The "Minerals" composed of organic chemicals!
- The
Mineraloids: The "Minerals" that lack crystal structure!
Mineral Identification
Physical
Properties
[Also from/to:
Amethyst Galleries,
Inc Copyright ©1998]
These are the physical properties most
useful for mineral identification:
- Color -
Not the best way to identify a mineral. Color can be
controlled by the smallest trace amount of a minor substance. A DISTINCTIVE color,
though, like that of pure sulfur, can be
useful.
|
Appearance is
a lousy way to identify minerals - general appearance can be deceiving.
|
Other Important Properties:
|
Hardness
The Mohs Hardness Scale
Is a list of the hardnesses of particular
minerals that can be used to classify other minerals (ranges from 1 to 10): |
