Birthstone of November;
State Gem of Texas- blue variety
Chemical formula: Al2SiO4(F,OH)2
Color: Colorless if pure, impurities cause the colors blue, brown, orange, gray, yellow, green, pink and reddish pink
Crystal system: Orhtohombic
Specific Gravity: 3.49- 3.57
Topaz is commonly associated with sillicic igneous rocks of the granite and rhyolite types. It is typically found in gigantic pegmatites and/or vapor cavities in rhyolite lava flows, including those at Topaz Mountain in western Utah. It is also found in fluorite and cassiterite in various areas including the Ural and Ilmen mountains of Russia, in Afghanistan, Sri Lanka, Czech Republic, Germany, Norway, Austalia, the United States and many other localities.
Some clear topaz crystals from the Brazilian pegmatites can reach boulder size and weigh hundreds of pounds. These crystals can be found in museums around the world.
The largest cut topaz is the American Golden Topaz which weighs 22,892.5 carats and has 172 facets. It is in the Smithsonian Institution. This is the third largest facetted stone in the world.
American Golden Topaz
The largest topaz is the El-Dorado Topaz weighing in at 31,000 carats. It originated in the mineral-rich southeastern state of Brazil, Minas Gerais. The original stone weighed 81.5 pounds when it was discovered in 1984. After cutting and polishing, it weighed only 13.6 pounds or 30,845 carats.
Next to the American Golden Topaz is the Golden Topaz Sphere. It is a sphere that is 12,555 carats that is gold in color from Brazil. It was cut in Idar-Oberstein, Germany and has over a thousand facets on it.Golden Topaz Sphere
Two of the largest topaz crystals are found are also in the Smithsonian Institute, one is the Lindsay Uncut Topaz which is 70 pounds and the Freeman Uncut Topaz which is 111 pounds. These are two of the largest stones of their color.
The photographer’s son is pictured with the two stones to show the size. At the bottom is the American Golden Topaz.
The largest facet grade topaz was found in Brazil in the 1930’s and has yet to be named or cut. Weighing in at 153 pounds, it is considered to be the first giant gem-quality topaz found. At over 350,000 carats, it remains to be cut. Sometime later, crystals up to four times its size were found and are still in Ferros, Brazil.
The most common topaz found in the commercial markets is blue topaz. Even though it is rare to find the blue in nature, they can irradiate it and turn it blue.
This is a typical Brazilian blue topaz.
The sliver pictured is a piece that has been irradiated.
According to the magazine, Colored Stones, blue topaz is the second most popular gemstone, surpassed by blue sapphire.