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www.mineralgallery.co.za Minerals P-T |
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Transvaal Jade (Grossular garnet) |
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Name
Transvaal Jade
(Massive grossular garnet)
Chemistry
Uses
As a gemstone and as an ornamental stone
Color
Green to blue to purple and sometimes brown
Hardness
7.5
Specific gravity
2.7
The first deposit that was opened was a deep jade color. Everybody thought that they have struck jade. So this grossular garnet was called Transvaal Jade. The Transvaal was one of the four provinces of the old South Africa.
Some of the material is less opaque. The consignment that we have can be viewed in our rough section. Here is some technical knowledge.
The garnets are a family of common and widespread silicate minerals found in metamorphic and some igneous rocks. The generalized chemical formula of garnets is XOYM (SiOP)O, with X indicating a divalent cation, such as iron, magnesium, calcium or manganese, and Y trivalent cation, such as aluminum, iron, or chromium. The SiOP indicates silica tetrahedrons. This is a silicon ion surrounded by four oxygen ions. The other atoms are packed between the tetrahedrons.
The ugrandites are rarer than the pyralspites. Grossular, containing calcium and aluminum, is found in clay-rich limestones that have been metamorphosed to marble and in some contact-metamorphic deposits, or skarns, formed when an igneous rock intrudes and reacts with limestone. Garnet is commonly cut as a gem (see gems). The dark red, Victorian garnet jewelry was made from pyrope garnets mined in Bohemia, now a part of the Czech Republic. Grossular makes hessonite, an attractive, cinnamon brown stone, and demantoid, the green variety of andradite, is rare and highly prized. Synthetic yttrium-aluminum garnet, or YAG, is used to imitate diamond as a gem. Garnet is also used as an abrasive.
The material that we have can be carved as an ornamental stone.
