Pseudomorph Goethite After Marcasite | Prophecy Stone | 45.8 gr | Farafra Oasis, Egypt Herkimer Dimensions: 62x57x41 mm / 2

Dimensions:  62x57x41 mm / 2

Those don't take away from how interesting this piece is

Dimensions:   61x39x28 mm / 2

Its dimensions are 29x22x13mm

Pseudomorph Goethite After Marcasite | Prophecy Stone | 45.8 gr | Farafra Oasis, Egypt Herkimer Dimensions: 62x57x41 mm / 2Pseudomorphs are mineral specimens that have the external shape of one mineral but are composed of another. The pseudomorph goethite after marcasite forms when marcasite is exposed to oxidizing conditions and starts to oxidize and break down. As the marcasite breaks down, goethite replaces it in the crystal structure, preserving the shape of the original marcasite crystal. The resulting specimen appears as a marcasite crystal, but is actually composed