we consider
it as limited to the natural history of simple minerals, or mineral
species. In the strictest sense, a mineral species is a natural
inorganic body, possessing a definite chemical composition, and
assuming a regular determinate form, or series of forms. Many
substances heretofore regarded as minerals will naturally be
excluded—such as all the artificial salts, the inorganic secretions of
plants and animals, the remains of former living beings now imbedded
in rocks. Many substances originally organic pro ducts have by common
consent found a place in mineral systems—such as coal, amber, and
mineral resins—which ought not to be the case; also some amorphous
substances, with no forms or chemical composition, as some kinds of
clay, have also been introduced into works on Mineralogy, but often
improperly, and with no beneficial result. Aggregates of simple
minerals or rocks are likewise excluded from the science of Mineralogy,
though the various associations of minerals, their modes of occurrence,
and their geological position, are important points in the history of
the different species. One most important object in Mineralogy is a
full description of minerals, their essential properties and
distinctive characters, as will enable the student to distinguish the
various species, and to.recognize them when they occur in nature.
The
gems, or precious stones, are obtained from minerals. It is
indispensable, therefore, to be fully acquainted with all the
characters which distinguish them from one another, which is
accomplished by the terminology or nomenclature of the science of
Mineralogy—that is, with the meaning of the terms used in describing
the properties of minerals, and the various modifications they may
undergo,
