Carnotite
Chemical compound
Carnotite is a potassium uranium vanadate radioactive mineral with chemical formula K₂(UO₂)₂(VO₄)₂·3H₂O. The water content can vary and small amounts of calcium, barium, magnesium, iron, and sodium are often present. Wikipedia
Colors: bright greenish-yellow
Crystal class: Prismatic (2/m); (same H-M symbol)
Crystal habit: Crusts, earthy masses, foliated and granular aggregates
Crystal system: Monoclinic
Formula (repeating unit): K2(UO2)2; (VO4)2·3H2O
Fracture: uneven
Luster: Dull, earthy; silky when crystalline