Pseudomorph Goethite After Marcasite | Prophecy Stone | 31 gr | Farafra Oasis, Egypt | SO24 Size:B Weight: 42

Weight:  42

Weight: 121 Grams / 4

but is actually composed of goethite

derived from the more primitive Agoniatitida during the Middle Devonian some 390 million years ago

Pseudomorph Goethite After Marcasite | Prophecy Stone | 31 gr | Farafra Oasis, Egypt | SO24 Size:B Weight: 42Choose your Pseudomorph! Pseudomorphs 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,