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| October--the Opal | ||||||||||||
| SiO2 with 8-12 % H2O | ||||||||||||
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| An opal is a noncrystalline gem. It has a hardness of 5 1/2-6 1/2. Opals range in color from white to grey to yellow to red to brown to black. Internal reflections cause them to shimmer. An opal is the only stone that shows all colors naturally. In some opals there colors can only be shown when the stone is wet. There are five types of opals. -precious opal--a precious gem -fire opal--an orange-red color -Australian opal--an iridescent blue color -Hyalite--a clear, glassy opal -wood opal--when siica replaces the branches of trees, preserving them Opals are commonly found in Australia and Mexico. |
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