- Luster is the sheen on the surface of the mineral
it may look metallic, glassy, dull or earthy, etc.
- Hardness is how resistant a mineral is to being scratched.
Some minerals like talc are very soft and can be scratched with
a fingernail, to others that are hard enough to scratch other
rocks. See Moh's Hardness Scale
- Streak is the color the mineral is when powdered,
it may be different than the color of the mineral.
- Cleavage is how the mineral breaks along its lines of
structural weakness. For example, Mica breaks in thin sheets,
and Calcite will break along its 3 plains of weakness looking
like a slanted rectangular box.
- Specific Gravity or Density of the mineral. You have two minerals that
are the same size, but one is heavier than the other, it is more
dense. For example, if you have a 1" cube of pyrite and
one of galena, the galena will feel heavier even though it is
the same size. It is more dense (or has a higher specific gravity).
- Magnetism of a mineral. You may have two minerals that
look almost identical, but one may be magnetic and the other
not. This will help you identify your minerals.
- Color of a mineral can be very deceiving, and should
not be used as the main tool for identification. For instance
a clear quartz crystal, and an amethyst crystal. The amethyst
is purple in color, but is also quartz.
- Other things like taste (example halite)
smell (example sulfur), opalescence, occurrences with other minerals,
etc.
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