Prehnite Custom Cut Cabochon. Image and work by Jim Colony at http://www.etsy.com/shop/JimColony
More often found in mineral collections than jewelry, prehnite is a luminous beauty and something a little different. A Dutch colonel, Hendrick Von Prehn, is credited with discovering prehnite in 1774 at the Cape of Good Hope in South Africa. He brought specimens back to Europe, and is the first person to have a stone named in their honor.
Prehnite is one of the more obscure members of the huge silicate class of minerals, and is a calcium aluminum silicate hydroxide (Ca2 Al2 Si3 O10(OH)2). Prehnite is in the phyllosilicate subclass, meaning that on the atomic level the crystals like to form sheets, seen in the more famous members mica and vermiculite. Prehnite is usually translucent and seems to glow from within like moonstone and chalcedony, other silicates. It typically occurs in shades of lemon yellow, grass or olive greens, and browns, but can also be clear.
Prehnite crystals. Specimen collected and photographed by Eric Greene. For sale at Treasure Mountain Mining: http://www.treasuremountainmining.com/
Prehnite formations are typically round and in China, the mineral is known as “grape jade” because the light green crystals can look like a bunch of grapes. On rare occasions, prehnite forms fingerlike projections that are sought after by collectors.
Prehnite finger crystals. Photo by Kevin Ward at The Mineral Gallery. Specimen for sale at: http://www.exceptionalminerals.com/denver2011-6.htm
Prehnite pops up all over the world in areas of hydrothermal activity, including South Africa, Mali, the United States (New Jersey and Connecticut), India, Germany, Scotland, China, Spain, and France. Gem grade material was rare until the recent discovery of several large African and Australian deposits, making the stone more available and popular in jewelry. Prehnite is not artificially created or enhanced, though there are stories of sellers applying oil to the stones to make them appear more lustrous.
Known as both the stone of unconditional love and the stone of prophecy, prehnite is supposed to give clarity and keep thoughts of the heart on a person’s mind.