Wulfenite

Wulfenite is a mineral composed of lead molybdate, with the chemical formula PbMoO₄. It is distinguished by its vivid colors, mainly shades of yellow, orange and red, although brown, gray or colorless specimens can also be seen. 

The density of wulfenite is around 6.7 to 7.0 g/cm³, making it a relatively heavy mineral. It crystallizes in the tetragonal system and forms mainly in the oxidized zones of lead deposits. With a hardness of 2.5 to 3 on the Mohs scale, it is relatively fragile, but its rarity and beautiful colors make it a sought-after mineral in collections.