Wulfenite, often occurs as thin tabular crystals with a bright orange-red to yellow-orange color, sometimes brown, although the color can be highly variable.  It can occur as a secondary mineral in oxidized hydrothermal lead deposits.  

This specimen from Yazd Province Iran is unique due to it's white calcite crust and tiny dots of Vanadinite if you look very close.

Pure wulfenite is colorless, but most all samples display colors ranging from a creamy yellow to a sharp, intense red. Some samples even display blues, browns, and blacks. The yellow and red coloration of wulfenites is caused by small traces of chromium. Others have suggested that while the lead adds little colors, perhaps the molybdate contributes to wulfenite’s yellow color.

Wulfenite was first described in 1845 for an occurrence in Bad Bleiberg, Carinthia, Austria and named for Franz Xavier von Wulfen (1728–1805), an Austrian mineralogist.