Pyrite

Pyrite is a very interesting mineral for many reasons. The name Pyrite comes from the Greek word “pyr” which means “fire,” and was named because it was found that sparks would fly from it if struck against another minerals like steel. In early times, this sparking ability gave people a way of creating fire, and in later times, this ability made it popular for use in early firearms devices like the wheel lock. Today Pyrite is called “Fools Gold” because throughout history people have mistaken it for Gold because of its similar visible structure, metallic surface and brassy yellow color.
The funny thing is Gold is often found with to Pyrite deposits. Pyrite can easily be distinguished from Gold. Pyrite is much lighter in color and much harder. Even though Pyrite is a fairly hard mineral, its crystals are known to break and crumble, because it is brittle. Pyrite is common in the Earth’s crust and found in almost every possible geological environment like sedimentary, metamorphic, magmatic and hydrothermal deposits. Pyrite’s usual crystal forms are cubic, octahedron and pyritohedron.
When a cube and pyritohedron crystal combine, the face of the cube appear to be grooved with lines. Many times Pyrite will be found in combinations of all these forms, but also can occur in masses, globular, radiating or reniform. Pyrite is also commonly found as small nodules. A mixture of this nodular form, and are called “Pyrite Suns” or “Pyrite Dollars”, are popular for collectors. Pyrite has the same chemical makeup as Marcasite but has a different structure, and shape. Pyrite is a polymorph of Marcasite and it can be extremely difficult to tell apart.

The name Marcasite came from the Arabic word for Pyrite. The confusion between the two minerals is common because the jewelry trade uses the name Marcasite, when they are actually selling Pyrite. Actual Marcasite can’t be used in jewelry because it is even more likely than Pyrite to crumble into a powder. Another mineral named Bravoite is very closely related to Pyrite, but contains 20% more nickel. Even though Pyrite contains a high percentage of Iron and is common, it is not used as a source for Iron today. It was mined as a source for Sulfur during WWII to produce sulfuric acid.
The Sulfur component of Pyrite was in high demand as a strategic chemical, and was found in parts of Tennessee. The Pyrite supplied them with enough sulfuric acid to get the job done. Pyrite can be used to make marcasite jewelry and it usually set in silver. Pyrite is always in the process of being created or destroyed. It is mostly a good mineral but does have its down sides. Sulfate released from decomposing pyrite combines with water producing sulfuric acid, which leads to acid rock drainage and potentially acid rain.
Pyrite also has caused problems for miners. The main issue is dust explosions brought from Pyrite. To prevent these explosions the miners spray limestone on the exposed coal surfaces. Pyrite has also been known to cause some structural damage, and did so in the U. S. , Canada, and Ireland. In 2009 problems with Chinese drywall imported into the U. S. after Katrina were results of oxidation of pyrite. Stone buildings containing pyrite have been known to turn brown. Other than a few problems, Pyrite is a beneficial mineral.