- Thaumasite (rough and cut set)
- NChwaning Mines, Kuruman, Kalahari manganese field, Northern Cape Province, South Africa
- Thumbnail, 0.7 x 0.4 x 0.4 cm (Crystal), 1.11 ct (Gem)
0.7 x 0.4 x 0.4 cm (Specimen); 1.11 carats; 9.67 mm x 5.08 mm (Gem) - Thaumasite is an uncommon mineral with an unusual chemistry as it has a composition of carbonate, sulphate and hexahydroxysilicate anions. The best and possibly ONLY gem material is from South Africa. These pieces are the finest known examples of Thaumasite extant, but crystals are rarely over 2 cm, and gems are few and far between. The crystal in this set is a well-formed, gemmy, terminated, hexagonal prism with a classic soft yellow hue. The stone is actually a bit larger than the crystal and has a beautiful "Cut Corner Rectangle" cut with only very very slight inclusions, and is nearly colorless. When one is collecting rare gems, Thaumasite is a must have, and this set would make a great addition to any collection, especially because the stone is over 1 carat in weight.