Topaz

This extraordinary topaz gem is labeled 22,892.5 carats. It is displayed in the Smithsonian Museum of Natural History and it's origin is Minas Gerais, Brazil. It is cut with 172 facets and has a mass of 4.6 kg and measures about 15 cm across. It is classified as American golden topaz, and the composition is Al₂SiO₄ (F,OH)₂, a silicate of aluminum.

Topaz has a hardness of 8.

Some of the topaz crystals which come out of Brazil are enormous! The tallest crystal at right is about 50 cm tall. And the crystal below is even bigger, measuring 60-70 cm across.

This topaz sphere measures 12,555 carats. The pale golden sphere has over 1000 facets, cut by a gem cutter in Idar-Oberstein, Germany in a location where there have been gem cutters since the 15th century.

The source of the topaz is listed as Minas Gerais, Brazil, the origin of so many other remarkably large crystals.

This example of a growth habit of topaz is from Thomas Range, Juab County, Utah. It is described as being formed with bixbyite. The overall sample size is about 10x5 cm.

The source of these topaz samples and gems is listed as Ouro Preto, Minas Gerais, Brazil.