Location: Gachalá, Cundinamarca Department, Colombia

Size: 3.45 x 2.77 x 2.29 inches

Large, penetration twinned, pentagonal dodecahedron Pyrite crystals to 6.5 cm. These striated Pyrite crystals are excellent examples of "iron cross" twins. The surface of the specimen has altered to goethite. This and many similar specimens came on the market in 2017. Twinned pyrites of this size were very rare before this find.

Pyrite also commonly called by its nickname “fool’s gold” is a brass-yellow colored mineral with a bright metallic luster. Its chemical composition is iron sulfide and is the most common sulfide mineral. It forms in both high and low temperatures and occurs in igneous, metamorphic, and sedimentary rocks across the world.

The name "pyrite" is after the Greek word “pyr" meaning "fire." It received this name because pyrite can be used to create the sparks needed for starting a fire if it is struck against metal or another hard material. Pieces of pyrite have also been used as a spark-producing material in flintlock firearms.

Pyrite main commercial use today is for the production of sulfur dioxide, in such applications as the paper industry, and in the manufacture of sulfuric acid as well as the cathode material in some non-rechargeable lithium batteries.