F - 37x29 mm - 17

This is a fantastic Fluorapatite crystal

The impact ejected material into the atmosphere

Weight: 242 grams / 8

Pseudomorph Goethite After Marcasite | Prophecy Stone | 72 gr | Farafra Oasis, Egypt | SO24 Uvite F - 37x29 mm -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, but is actually composed