Hornblende
Hornblende
is actually the name given to a series of minerals that are rather
difficult to distinguish by ordinary means. The iron, magnesium and
aluminum ions can freely substitute for each other and form what have
been distinguished as seperate minerals. The minerals are given the
names Magnesio-hornblende, Ferrohornblende, Alumino-ferro-hornblende
and Alumino-magnesio-hornblende. These minerals are obviously named
for their chemistries although there is little to distinguish them in
the field. The iron rich members of the series are more darker black
and less likely to be translucent.
Hornblende is not often a collection mineral because good crystals
are somewhat difficult to find even though the mineral is widespread.
It is almost always opaque and black and not very attractive. However
a few specimens are extraordinary and make for valuable specimens.
Some crystals can grow to a fairly large size of several feet long and
nearly a foot across. Other specimens of hornblende can be acicular
clusters or needle thin crystal aggregates. Many times a specimen of a
more valuable mineral will be accented by the opaque black crystals of
hornblende.
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