Chemical
discoveries very much assisted the right classification of minerals,
introducing in the science a new law, founded on analysis, which helped
to confirm or slightly modify that which had been already established
as to crystalline forms. Berzelius, Weiss, Becquerel!, Ebelmèn,
Brewster, Mitscherlich, Brocchi, Spada-Medici, Pouzi, and a number of
learned men of every other nation contributed to the advancement of the
science.
Now,
the learned, generally speaking, divide minerals into three classes :
the first contains combustible minerals; the second, metals; the third,
lithoids or stones. These three classes are subdivided, as we have
already remarked, into genera, species, and varieties.
To
the first class belongs the genus of carbonates, which is divided into
four species, the first of which is carbon, properly so called, and of
which one of the varieties is the cubic carbon, otherwise the diamond.
The
third class distributes stones into twenty-four different genera, which
are subdivided into many more species and varieties. For the sake of
brevity we shall refrain from giving the denomination of each of these
twenty-four genera, or orders, as they are called by others.
It is sufficient for us to know that amongst these orders are the alumina, the silicates, and the fluorites.
To
the alumina belongs the species of corundum, of which the ruby, the
sapphire, and, in short, all so-called oriental gems are varieties.
Amongst the silicates is pure silex or quartz, from which is derived
