Pseudomorph Goethite After Marcasite | Prophecy Stone | 66.7 gr | Farafra Oasis, Egypt Fluorite before entering the Earth's atmosphere

before entering the Earth's atmosphere

83-gram Kara Crater Impactite specimen from the Yugorsky Peninsula in Nenetsla

6 inches  Weight:  7

Bead Size: 6-9 x 4

3 Grams / 7

Pseudomorph Goethite After Marcasite | Prophecy Stone | 66.7 gr | Farafra Oasis, Egypt Fluorite before entering the Earth's atmospherePseudomorphs 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