Wulfenite
Wulfenite is a lead molybdate mineral with the formula PbMoO₄. It often occurs as thin tabular crystals with a bright orange-red to yellow-orange color, sometimes brown, although the color can be highly variable. In its yellow form it is sometimes... Wikipedia
Chemical formula: PbMoO4
Birefringence: δ = 0.122
Cleavage: On, distinct; on,, indistinct
Color: Orange-yellow, yellow, honey-yellow, reddish-orange, rarely colorless, grey, brown, olive-green and even black
Crystal class: Dipyramidal (4/m); H-M symbol: (4/m)
Crystal habit: Thin tabular to pyramidal
Crystal system: Tetragonal