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Birthstones For October
Precious Opal and Pink Tourmaline are both listed as birthstones for
October. The Opal may be white, with a play of colors giving it the name
of fire opal, or it may be black. The physical structure is somewhat
uncertain. Nevada and Idaho are the principal American sources, while
Australia leads the foreign sources.
The Pink Tourmaline is usually a transparent gem stone with a variety of
colors. Some opaque forms occur. Coarse granite rocks in San Diego County
in California and Maine are the best sources. Its hardness is 7 to 7.5.
It has an uneven to conchoidal fracture, and a poor cleavage.
-- by Axel E. Janson
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