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68 TOURMALINES
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As
a mineral it occurs in an opaque form, colored either black or brown,
and is quite common as a rock-forming mineral, resembling somewhat in
its occurrence in this form, horn-blend. These crystals often possess strange and beautiful qualities, notably that of having a strong dichroism, that
is, the same crystals often have different colors, being at one end red
and at the other end green; or, on the other hand, the crystal may show
a blue center, then a colorless zone, and then one red and one green,
and furthermore the crystal will always show two different colors
according as it is viewed from one angle or another. The beauty of
these changing colors is often very striking, and is the chief cause
which has led the tourÂmaline to be widely appreciated as a gem.
In
the cutting of the gem skill is necessary in order to so cut the
specimen that it will exhibit its most beautiful color. The most valued
colors are, as a rule, dark red, sometimes almost approaching that of
the ruby, and dark green shading to blue or yellow.
One
of the chief localities for the mining of the gem tourmaline is Paris,
Maine. The disÂcovery of this source was mainly accidental. Two boys of
the neighborhood, Elisha L. Hamlin and Ezekiel Holmes, had for some
time been
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