Tanzanite

タイトルまたは説明

Tanzanite is the blue/violet variety of the minerak zoisite (a calcium aluminium hydroxyl Soroslicate)belonging to the epidote group. It was discovered in the Mererani Hills of Manyara region in Northern Tanzania in ***7, near the city of Arusha and mount kilimanjaro Tanzanite is used as a gemstone. Naturally formed tanzanite is extremely rare and is endemic only to the Mererani Hills.
Tanzanite is noted for its remarkably strong trichroism, appearing alternately sapphire blue, violet and burgundy depending on crystal orientation. Tanzanite can also appear differently when viewed under alternate lighting conditions. The blues appear more evident when subjected to fluorecent light and the violet hues can be seen readily when viewed under incandescent illumination. Tanzanite is usually a reddish brown in its rough state, requiring artificial heat treatment to bring out the blue violet of the stone.