The mineral Idocrase has another name, Vesuvianite, which is a charming mineral, originally discovered on the volcano, Mt Vesuvius, which earned its other name. The name Idocrase was a Greek name which meant “mixed form,” a reference of its crystal form exhibiting a blend of other forms of minerals. The crystals are of the class of tetragonal symmetry, having a square cross-section, when cut along its vertical axis. These tetragonal crystals are rare. Luckily Vesuvianite is obtained in well-formed crystal shapes.
Unusually, few of its crystal structures have resemblance to the grossularite, which is a giant isometric mineral. The interesting fact is that its crystal structure is composed of the Si207 and Si04 groups. Because Vesucianite belongs to the Si04 group it is classified among the nesosilicates. However, organizations of the higher class of Si207 groups placed it in the sorosilicate subclass.
The formation of Vesuvianite is on account of the metamorphic contact with tainted limestone, and it is normally seen along with some exotic minerals. A huge green colored type of gem is named Californite , referring to the place it occurred. To a certain extent it is a lovely and rare mineral that many mineral collectors envy.
Prominent Occurrences: Quebec, California, Canada, and the recent New England district of the USA; Italy, Mt Vesuvius, Urals, Switzerland and Russia.
Derivation of Name
Vesuvius was named so because it was initially found contained with blocks or near to lavas on Mount Vesuvius.
Ca10 (Mg, Fe) 2Al4 (SiO4) 5 (Si2O7) 2 (OH, F) 4
Color – Violet, pink, brown, yellow, green with blue hue, white to colorless, black, red and usually zoned
Crystal System: tetragonal; 4/m 2/m 2/m
Crystal Habits: Crystals are on the prismatic forms, the entire cross-section is square. Generally it is formed by two pairs of prisms having four sides, of which one is leading.
Luster – Resinous to Vitreous
Fracture - Irregular to Sub conchoidal
Transparency – Translucent to Sub-transparent
Associated minerals – Diopside, Epidote, Spinel, Grossular, Wollastonite, Scapolite, and Calcite.
The Value, use and price of Idocrase differ to a great extent, on the quality and size of the gemstone. The best quality of colored stone is available from any part of the world. You get it from Bangkok at the wholesale rate. Premium Jewelry is initiated from the finest gemstones, and this depends on the reputation of the gem store from where you obtain it.
Purchasing your Idocrase loose rather than in sets, ensures that the best is purchased for the price you are paying for it. Gemstones in the loose forms are not so expensive, they are valued better, and it is worth the price you are paying for them.