The term prase (or prasem) is used to describe lustrous, cigar- and spear-shaped quartz crystals with green hedenbergite inclusions. The prase found on Serifos Island, in the Cyclades islands in Greece, is considered the best ever found in the world; it is often aesthetically sculpted, with dramatic visual appeal. Specimens from Serifos are featured in mineralogical museums around the world.
Originally, the varietal name “prase” was applied to a leek-green colored quartzite (a rock, not a mineral). Now it is simply a color descriptor for quartz: If it is sage- or leek-green, it is called “prase” – no matter what causes the color. The color of prase is caused by various green inclusions, more or less evenly distributed throughout the interior of the crystals. Quartz with chlorite inclusions, however green it may be, usually does not count as prase. The most common inclusions seem to be fibrous amphibole minerals like actinolite, or the pyroxene mineral hedenbergite. Since the fibrous inclusions interfere with normal crystal growth, prase crystals often have peculiar and characteristic shapes that are very helpful in determining the provenance of the specimen.
Prase is found at only a very few locations. The most famous ones are the Island of Elba, Italy, and the Island of Serifos, Greece, located in the south Aegean Sea. Other locations include Dalnegorsk, Russia, and Morocco. Perhaps the best site in the world for green quartz is the quartz deposits of Avessalos, on Serifos Island. Other minerals found in this mine include hematite (sometimes in small rosettes), andradite and amethyst. Other notable localities for prase on Serifos include Mega Horio, Megalo and Mia Chorio. Serifos Island, located in the south Aegean Sea, represents a multiple mineralized district including intrusion-hosted skarn rocks that formed when magma of igneous rocks intruded into carbonate rocks.
Prase crystals from Serifos have a peculiar shape. They are elongated and rarely show individual rhombohedral faces at their terminations. Instead, the ends look like pointed or blunt bundles of many small crystals. The overall shape can be cigar-like, hourglass-like, or sharply pointed spears. The crystals typically sit on a grey-green matrix of hedenbergite (or, possibly, actinolite).
In Tucson in 2008, I acquired a large lot of specimens from a Greek miner who managed to get the necessary permits & permissions to run a month-long, hand-scale mining operation at Avessalos during the summer of 2008. This fellow excavated the floor of the large, shallow cave where prase crystals had been found years ago. By the time he scraped bottom, there was nothing left to mine, and he had a bunch of really fine, new crystals from this old classic locality. I was told that the lot I inspected was the last of the crystals that could be mined – at least without drilling, blasting, and heavy equipment which would be cost prohibitive. So, considering the circumstances, I picked out all the crystals that I liked from the lot – the ones with sharp terminations, vibrant color, and aesthetic sculptural arrangements. We now have many of these available in sizes from small miniatures to cabinet specimens, and will be selling them until they are gone. And that, unfortunately, will be the end!
Because of their scarcity, and because of the unlikelihood of reopening any of the mines on Serifos, prase crystals from this locality are now considered to be classics, and are highly sought after by mineral collectors. You can see some of the green quartz specimens we have available here in the Prase Quartz Gallery on our website www.treasuremountainmining.com.