Iron Cross Twin Pyrite Goethite after Pyrite Pseudomorph (LOT: PY-82)

Iron Cross Twin Pyrite, otherwise known as Goethite PS. After Pyrite, is pseudomorph pyrite, meaning it has been replaced with goethite on the surface.“Iron-cross twins” are twinned crystals exhibiting the forms of two interlocking pentagonal dodecahedra (also known as pyritohedra). These twins display edges crossing at 90 degrees, and in an idealized/model twin, these edges form a cross. In nature, the edges that form the cross are sometimes not continuous or are not equal to one another, so a pyrite crystal that is twinned according to the iron-cross law may or may not exhibit an actual cross shape, but in any event the relationship of the crystals exhibits the “crossed” symmetry.

The iron cross twin law is well known and exhibited in specimens from a few localities, but rarely does one find good-sized complete crystals. 

LOT: PY-82

1023g

x6 pieces

These remarkable specimens are from the Gachalá mine in the Cundinamarca region of Colombia 🇨🇴