Marcasite

Although Marcasite is often referred to as a gem it is not. There are not any Marcasite gems on sale anywhere because this mineral is not desirable for the production of gems. If there is an advertisement for Marcasite gems the seller is really referring to pyrite which is used as a gem. Instead of searching for Marcasite jewelry, look for pyrite jewelry.

Marcasite is often referred to as white iron pyrite but it is lighter than pyrite and more fragile. Marcasite a bit more brittle than pyrite so it has a tendency to not be as stable, thus making it undesirable for jewelry. Even though marcasite is of the same chemical formula as pyrite it crystallizes in a different manner meaning that it is a totally different type of substance.

Marciste is never really used as a gem. Instead marciste is a primary and secondary mineral. It grows in nodules, concretions and crystals and a number of other sedentary rocks when it is a primary mineral. When marciste is a secondary mineral it is created through changes in chemicals that occur in the primary form of a mineral.

Marcasite is usually pale yellow in color, almost white, when it is seen on surfaces. It has a luster that shines and tends to turn a yellowish or brown color when it tarnishes. Marcasite is hard and rigid and the small crystals are bunched together in spaces that are called cockscombs.

Marcasite is found in sedimentary rocks in places around England. Crystals of Marcasite form in chalk and can be located within hydrothermal veins that have low temperatures. Marcasite is so brittle that even a blade can not be used to scratch the surface.
Pyrite decay is a stage that Marciste can go thorugh in which marciste becomes a white poweder. This is another reason why it is undesirable for jewelry. However, there is no way of tellign when or if Marcasite is going to disintegrate. Certain marcasite experience this phenomenon when moiture mixes with the sulfur in marcasite. Sulfuric acid is the result of this process and it will work to destroy the rest of the marcasite.
Although marcasite is not a gem it is an interesting mineral to study. Find out more about marcasite and when it is used for online. When buying jewelry, if marcasite is advertise this is a warning sign. Question the jeweler about what type of marcasite jewelry they offer and beware of any purcahses from delers that do not know their gems from their minerals.