Natural Idocrase

Idocrase, is a fascinating mineral found originally on the volcano Mt Vesuvius from which it derives one of its names (Vesuvianite). Found in shades of green and sometimes yellow-brown or pale blue it often resembles peridot in color. The name Idocrase, is Greek in origin and means of mixed form, an allusion to its crystals showing a mixture of other mineral forms. Its crystals conform to the tetragonal system and show a square cross-section perpendicular to the long axis. Idocrase was first identified in 1795 by the world renowned German geologist, Abraham Gottlob Werner who was also responsible for the discovery of Chrysoberyl and its varieties.

Find your Idocrase

Our Idocrase(s) are available in various shapes, sizes and colors. 21 Idocrase(s), too many to look through? You may select any combination of search options. Colors grade into each other and you can search for more than one color at once. For a better selection, try selecting two or three colors, -- your first choice plus the two closest colors.

Idocrase Profile

Color information:	normally green, but also can be brown, yellow, blue and/or purple.
Refractive Index:	1.71 - 1.73
Chemical Composition:	nesosilicate or sorosilicate
Hardness:	6.5
Density:	3.3 - 3.5
Crystal Group:	Tetragonal
Ocurrence:	Quebec, Canada; Mt. Vesuvius; Italy; The Ural Mountains of Russia; China, Norway, Pakistan, Sweden, Switzerland, Kenya, Tanzania, and in the United States in California, Arkansas, Maine, Vermont and New Hampshire.
Sign of the Zodiac:	Sagittarius
Month of the year:	N/A

Gemologically, Idocrase is a complex mix of elements including oxygen, hydrogen and fluoride. It belongs to the silicate group of minerals and is defined more specifically as a calcium aluminum silicate. Its specific gravity ranges from 3.32 to 3.47, also in a range similar to peridot. With a hardness of 6.5, Idocrase is slightly softer than quartz. Although Idocrase crystalizes in a tetragonal structure massive forms are not uncommon and African material may be difficult to distinguish from some forms of grossularite. The vitreous to resinous luster of Idocrase is another of its distinguishing features. Idocrase is found at a number of locations throughout the world and may be related to limestone deposits, contact metamorphism, or volcanic activity. Some of the most notable gem quality deposits come from Quebec, Canada, and Mt. Vesuvius in Italy. Other sources include the Ural Mountains of Russia as well as China, Norway, Pakistan, Sweden, Switzerland, Kenya, Tanzania and in the United States; California, Arkansas, Maine, Vermont and New Hampshire. More recently, finds of Kenyan and Tanzanian Idocrase have brought some fairly transparent specimens to the market but not in significant quantities. The Jeffrey Mine in Quebec, produces a fine facet grade yellow-green material as well as a chromium-rich emerald-green variety and an extremely rare violet to lilac colored variety. A massive compact form resembling jade is referred to as “californite” or “California jade”. Chromium-rich idocrase is known as chrome vesuvianite, and a rare blue variety is known as cyprine. “Mangan vesuvianite” is a reddish to purple variety of manganese-rich idocrase. In the world of metaphysical gems, idocrase is more often referred to as Vesuvianite. It is an astrological gemstone associated with the signs of Sagittarius and Capricorn. It is believed to help clear negative energy and thoughts, and to alleviate anger, depression and fear. Idocrase is always popular among collectors but less known in the mainstream market. It is not known to be treated or enhanced in any way and is among the gemstones which remain completely untreated from the mine to the market.

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