dant
supply renders it of little value, the gem nevertheless possesses
every quality necessary for ornamental purposes. There are many
varieties of this stone, which are distinguishable by their
colour, and also by the difference of their chemical composition. The
garnet belongs to the monometric or cubic system of crystallization,
and is mostly found in rhombic dodecahedral crystals ; when in a matrix
its cleavage is dodecahedral; it is also found massive and in
small pebbles in rivers and alluvial deposits, occasionally (as in the
pyrope) in lamellar cleavable masses. Its hardness varies from 6.5 to
7.5; it scratches quartz slightly, and is scratched readily by ruby or
sapphire. Its specific gravity varies from 3-5 to 4.3 ; its
lustre is vitreous, in some varieties resinous, as in colophonite—a
name applied to a garnet found in Norway and America. This gem occurs
in many colours,—red, brown, yellow, white, green, black; the streak is
white; the diaphaneity varies from transparent to subtranslucent, or
nearly opaque, and it has a subconchoidal or uneven fracture. The
garnet is susceptible of positive electricity by friction, and has a
sensible effect on the magnetic needle. The varieties used in jewellery
are called carbuncle, cinnamon-stone (or essonite), almandine, and
pyrope or Bohemian garnet ; besides these, there are the leucite, the
melanite, the colophonite, the grossularite, the uwarowite varieties,
which are only interesting to the mineralogist.
The chemical composition of the several varieties differs according to the colours and peculiarities. The
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