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Zincite is a rare mineral that is insignificant from all but one region in the world....  More

Zincite is a rare mineral that is insignificant from all but one region in the world. Its bright orange color is very distinctive, as are its mineral association and habits. Pure synthetic Zincite is colorless; its natural orange to red color is caused by impurities of manganese oxide.

Zincite often forms together and is admixed with Franklinite. A typical association is spotted Zincite and Franklinite on a white Calcite matrix, sometimes joined with Willemite. Although Zincite does not fluoresce, its Willemite and Calcite associations are highly fluorescent. Synthetic Zincite has been produced from industrial operations and laboratory production, and this material is very aesthetic and widely available on the mineral market. Much of this material is brightly colored and comes from Poland.
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Zircon is a well known mineral that makes an important gemstone of of many colors. It...  More

Zircon is a well-known mineral that makes an important gemstone of of many colors. Its brilliant luster and fire, combined with good hardness, make it a desirable gem. Natural Zircon with good color and transparency is uncommon; most Zircon crystals are opaque and brownish. However, most Zircon gemstones, especially the blue and white forms, are enhanced by heat treatment.

Zircon often contains traces of radioactive elements in its structure, which causes it to be metamict. This unstable form of Zircon, called Cyrtolite, is characterized by rounded, almost dome-shaped crystals which are dull or pitchy in luster. When heated, these metamict Zircon crystals become stable, and revert to their normal crystal structure. Radioactive Zircon that has undergone a metamiction process is sometimes called "Low Zircon", and stable Zircon with an intact crystal lattice "High Zircon".

The dark brown to black color observed in most Zircon crystals is caused from iron oxide impurities. The green coloring in many rounded pebbles usually indicates the Zircon is radioactive variety. An interesting habit occasionally exhibited in Zircon from a few localities is that their color darkens and their luster dulls upon prolonged exposure to sunlight. This effect can be reversed by giving the stones a second heat treatment.

For additional information, see the gemstone section on Zircon.
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Zoisite owes much of its popularity to a beautiful blue variety that was first discov...  More

Zoisite owes much of its popularity to a beautiful blue variety that was first discovered in 1967. This new discovery in Tanzania brought forth a previously unknown color and habit for this mineral. The variety was unofficially named Tanzanite after the county it was found in, and it became an ever-popular gemstone sensation shortly after its discovery. The color of Tanzanite is rarely natural; it is almost heat treated from grayish or brownish hued stones. The heat treatment process removes unwanted color tints and strengthens the desirable blue.

Zoisite occurs in many other colors, and another well-known form is the pink, manganese-rich variety called Thulite. Another interesting variety is the deep green massive form associated with contrasting red Ruby. Zoisite was named in 1805 after Austrian scientist and naturalist Baron Sigmund Zois von Edelstein (1747-1819), who had a notable mineral collection and identified Zoisite as being a unique mineral species.
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