Variscite

Variscite forms near the surface where phosphate-bearing waters react with aluminium-rich rocks, usually as cryptocrystalline masses, nodules, veins or cavity fillings. Its type locality is the Meßbach quarry in the Vogtland district of Saxony, Germany. The International Gem Society names Utah as the principal source of gem-quality material, with nodules up to 24 inches across from Fairfield; other sources include Nevada, Arizona, Arkansas, California, Pennsylvania and Wyoming in the USA, and Queensland (Australia), Austria, Brazil, China, the Czech Republic, Germany, Sardinia (Italy), Peru, Poland, Spain and Tajikistan.

Variscite often occurs in the same areas as turquoise and can look very similar, but it is usually greener. Standard tests separate them: variscite gives a spot refractive index of about 1.57 versus about 1.61 for turquoise, may show absorption bands near 690 and 650 nm, usually appears weakly pinkish through a Chelsea filter, and is softer. Common turquoise treatments can mask these differences. Utah material is sometimes sold as "utahlite" or "lucinite"; variscite mixed with quartz is called "amatrix". "Synthetic variscite" offered online may be a simulant rather than a true lab-grown material.

With a hardness of only 3.5 to 5, variscite scratches easily, so it suits pendants, earrings and protective settings better than rings or bracelets, and should be stored away from harder gems. It is porous and can be discoloured by skin oils and cosmetics. Clean it only with a soft brush, mild soap or detergent and warm water.

Variscite is named after Variscia, an old name for the Vogtland district of Germany where it was first found. According to the International Gem Society, it has been used for jewellery since Neolithic times, more than 6,000 years ago: Neolithic beads found in Brittany, France, were called callaïs after a gem described by Pliny the Elder and were first thought to be turquoise, and some of this variscite came from Sardinia, pointing to a wide prehistoric gem trade in Europe.