Preciosa

The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS2.

Marcasite jewellery has a history that stretches back hundreds and hundreds of years. It was popular during the 18th century and was frequently seen in lockets, brooches, and cameos.
Preciosa is building on the more than one hundred-year tradition of cutting stones in North Bohemia. It is continuing the work of generations of craftsmen and, by introducing new, modern methods, is giving their art a new dimension. Its wealth of experience and a demonstrable commercial success have predetermined it for extending its assortment to another genuine material – Marcasite.

Category: Sulfide mineral
Chemical formula: Iron disulfide (FeS₂)
Color: Pale brass yellow, dull gold
Crystal habit:  Cubic, faces may be striated, but also frequently octahedral and pyritohedron. Often inter-grown, massive, radiated,
granular, globular and stalactitic.
Crystal system: Isometric; Pa-3
Mohs Scale hardness  6 – 6.8 ° 
Luster: Metallic, glistening
Specific gravity: 4.95 –5 .10
Refractive index: Opaque