Re: Yes, there is a Mineral Definition

Hi Bob, An ideal mineral would be composed of one or more of the chemical
elements AND those elements should be arranged in an orderly fashion which
is then called a crystal. Furthermore, the mineral should be entirely
naturally occurring (no intervention by Man in its creation). A rock can be
an aggregate of crystals (which can be either a single type or several
types.), or be a glass, or have organic substances in its make-up. Minerals
in a rock can be well formed crystals or pieces of crystals, depending on
the rock type. Naming rocks is an exercise in ZEN for you must consider  its
origin as well as its composition and fabric (texture).

However, as we study materials found on our planet, there are materials that
do not fit into the definition exactly. For example, Gold found in nature
may have a specific composition but was smashed by the action of moving
gravel and boulders so that its internal crystal structure is no longer neat
and orderly. We still call it a mineral (native element).

Some minerals are formed either directly or indirectly by the action of Man
or other life forms and might be placed in the realm of "organic minerals",
especially those substances that contain carbon in its composition. A
substance like coal does not have a definite crystal structure so it is not
considered a mineral. Your petrified wood is actually wood REPLACED by one
or more minerals, usually quartz. Exoskeletons of various animals may be
composed of calcite , a mineral, or of organic substances. These also may be
subject to change by geological processes and converted or replaced by
various minerals. I have a crinoid from Arizona that was completely replaced
by azurite.It is considered a fossil. I have a shark's tooth that still has
its original organic composition and it too is considered a fossil. A fossil
is independent of its make up. It just has to be some evidence of past life.
Bone is calcium phosphate and when that substance forms nice crystals it is
called the mineral apatite. Most dinosaur bone, like the petrified wood, is
replaced by quartz minerals and little or no apatite remains.

The definition of a mineral is a relic of the days when scientists and other
learned men were searching for the Fundamental Laws of the Universe. Since
then many sciences have relaxed or evolved in their thinking to include
working premises, rules, effects, probabilities and uncertainties.This kind
of thinking allows the science and scientists to get on with it and not be
bogged down trying to decide if opal is a mineral, mineraloid, amorphous
substance, or...? Hope this helps, Will Estavillo



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