Vesuvianite

Vesuvianite (idocrase) is a silicate mineral containing calcium, magnesium and aluminium. It takes its name from the crystals first found on Mount Vesuvius; Abraham Gottlob Werner described it under this name in 1795. Its colours range from yellow, green and brown to blue, violet and pink. It usually forms short pyramidal or long prismatic crystals in skarns, the rocks formed where limestone meets magma; its jade-like massive variety is called “californite” and its sky-blue variety “cyprine”.

Ornamental stone: Transparent, clean green and yellow crystals are cut as gemstones; the jade-like massive californite is polished and used as an ornamental and carving material. Collecting: Well-formed, many-faced crystals are sought after for mineral collections. Science: As part of the mineral assemblage in skarn deposits, it helps in understanding the conditions of rocks formed where limestone meets magma.

It has a hardness of 6–7 on the Mohs scale. It can scratch glass; a steel knife scratches it only with difficulty. Its specific gravity is 3.32–3.43 g/cm³.

Its best-known localities: Vesuvius and Monte Somma, Campania, Italy; Jeffrey Mine, Val-des-Sources (Asbestos), Québec, Canada; Ala Valley, Piedmont, Italy; Mont Saint-Hilaire, Québec, Canada; Vilyuy River area, Sakha (Yakutia), Russia.

Known localities in Türkiye: Camiboğazı skarn deposit, Gümüşhane, Türkiye.

Tetragonal crystals: short pyramids or long prisms with a square cross-section; a single crystal can show nearly 30 different faces. Its hardness is 6–7: a steel knife cannot scratch it. Its colour is mostly green, yellowish green or brown, and often changes in zones. Its lustre is between glassy and resinous; its cleavage is very poor, and it breaks with a subconchoidal surface. The jade-like massive vesuvianite (californite) is sold as “California jade” or “American jade”; these names are misleading, because it is not true jade (nephrite or jadeite).

On the “street to diamond” value ladder it sits on step 5 of nine: Ornamental stone. As an ornamental stone the value of vesuvianite depends on colour (vivid green and the rarer blue or violet tones), translucency and clarity, quality of cut and size; the name of the locality also matters. In jade-like massive californite, evenness of colour and quality of polish are sought. Collectors value well-formed, bright, undamaged crystals, especially from famous localities such as the Jeffrey Mine in Canada.

Today crystal-therapy sources present vesuvianite as a stone that calms anger, claiming that it brings emotional balance and disperses repetitive negative thoughts. The same sources link the stone with the heart chakra, say that it makes it easier to express love, and note that it has been given as a gift to newlyweds. None of these claims can be measured or tested; it has not been shown that a stone calms anger or disperses thoughts. If anger or anxiety makes daily life difficult, support should be sought from a professional. The truly interesting thing about vesuvianite is that it crystallised in rock blocks within or beside the lavas of Vesuvius, in rocks transformed by the heat of magma. This section reports beliefs; it is not health information. There is no scientific evidence for these claims and no stone replaces medical treatment.