Idocrase

Part of speech: noun

Definitions

1. A brown, green or yellowish silicate mineral that forms in metamorphic rocks and is also known as vesuvianite
2. A calcium aluminium silicate mineral, often found in crystalline form in contact-metamorphosed limestones and volcanic rocks
3. Vesuvianite, a complex silicate mineral prized by collectors for its tetragonal crystals and gem-quality varieties

Etymology: Idocrase is a mineral name coined in 1800 by the French mineralogist René Just Haüy, who built the term from Greek roots: "eidos", meaning "form" or "appearance", and "krasis", meaning "mixture" or "blend". Haüy's name points to the mineral's tendency to look like other minerals, which is why it was given a name about its shape rather than its chemistry. The sense of "blending" reflects a long-standing mineralogical habit of naming crystals for their resemblance to other substances. The mineral is better known by its other name, vesuvianite, which came from Mount Vesuvius, the volcano near Naples where it was first found in volcanic ejecta. The two names were used side by side for much of the nineteenth century, and "vesuvianite" is now the formal name in many mineralogical references, while "idocrase" survives mainly in older texts and in gemological and collector usage.

Synonyms: vesuvianite