Marcasite: Not What You Think! |
Marcasite is often confused with pyrite, but it differs in symmetry and shapes of the crystals although pyrite has similar characteristics. Over the course of time it can turn to pyrite, and also if it is heated. Marcasite cannot be used in jewelry as it will crumble, but the trade name "marcasite" continues to exist. The so-called marcasite or pyrite consists of tiny stones which are polished and set into silver for rings, bracelets, necklaces, and other jewelry.
Pyrite, the most common of sulfide minerals, is often located in veins of quartz, coal beds, and sedimentary and metamorphic rock, It gets its name from the Greek word "pura" meaning fire. It is often crystallized in striated cubes, and has a hardness of 6 on the Mohl's scale of hardness. It is light yellow with a metallic luster. It is often mistaken for gold, and therefore gets the name "fool's gold". It is a polymorph of marcasite which means it is made of the same chemical compounds which are arranged differently than marcasite. It is the most famous polymorph blend since that of diamond/graphite.
Particularly nice pyrite crystals have been discovered in Leadville, Colorado; Rio Marina on the Island of Elba; and Park City, Utah. The name Cathedral pyrite was given to large Leadville cubes which had Gothic faces. Falun, Sweden produced a pyrite which was rich in cobalt. Mexico and Bolivia have also been important sites of pyrite. It was once used as a source of sulphur for sulphuric acid, because, when exposed to the surroundings during mining, it reacts with oxygen and water to form the acid. It is also used to produce sulphur oxide for use in the paper industry. It is brittle, and when in a powdered state smells of sulphur. It is a common associate of all metallic ores, and sometimes is known to contain a small amount of gold. Such pyrite is called "auriferous pyrite."
Marcasite is relatively rare. and can be found in the United States, Russia, England, and Peru. One of its specific features are twinned crystals which resemble a rooster's comb, and are called "Cox's comb". Crystals are in large chunks, but most are of rock size. It is lighter than Pyrite and less a golden color. It has been around since civilization began; was frequently mined in China; and the Greeks used it as a good luck talisman. It is a brassy yellow color but also comes in green. Native Americans sometimes craft ornaments from Marcasite, although it will crumble after a certain period of time. Like pyrite, when in powder form it also smells of sulphur. Pyrite was also used in early firearms because when struck against a rock it produced a spark.