For example: -Autunite (hydrated calcium uranyl phosphate) with formula: Ca(UO 2 ) 2 (PO 4 ) 2 ·10-12H 2 O is a yellow - greenish fluorescent mineral with a hardness of 2 - 2œ. Autunite crystallizes in the tetragonal system and often occurs as tabular square crystals. - Aragonite is a