22196 - Calcite Geode with Gypsum Crystal 680 g in Natural Matrix Sphenopteris Petrography: (A

Petrography: (A

Otarion diffractum

Precious tooth of Eremiasaurus heterodontus (Mosasaur) from the phosphate deposits of the Ouled Abdoun Basin (Morocco)

Spectacular example of tooth belonging to an individual of Spinosaurus

inside his own jaw bone

22196 - Calcite Geode with Gypsum Crystal 680 g in Natural Matrix Sphenopteris Petrography: (ASIZE: 142. 6 mm 5. 61 in WEIGHT: 680 g Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3). The Mohs scale of mineral hardness, based on scratch hardness comparison, defines value 3 as "calcite". Other polymorphs of calcium carbonate are the minerals aragonite and vaterite. Aragonite will change to calcite over timescales of days or less at temperatures exceeding 300 C and vaterite is even less stable. Gypsum is a