Tarnowitzite is a plumboan (lead) variety of Aragonite. It was named in 1841 by August Breithaupt for the type locality at Tarnowskie Góry (Tarnowitz), Upper Silesia (Slaskie), Poland. Tarnowitzite is found as pseudo-hexagonal pyramidal twinned crystals often associated with Calcite, Dolomite, Duftite, Galena or Smithsonite. It is colorless, white or cream to tan colored with vitreous luster. Mineral specimens of Tarnowitzite are very attractive but it is very rarely available as a faceted gem.

Locations for finding Tarnowitzite: at Fryderyk Mine (Friedrich Mine), Tarnowskie Góry (Tarnowitz), Upper Silesia (Slaskie), Poland; Trzebionka mine, Trzebinia, Chrzanów District, Malopolskie, Poland; Pomorzany Mine, Olkusz, Olkusz District, Malopolskie, Poland; Tsumeb Mine, Tsumeb, Otjikoto Region, Namibia; Touissit, Touissit District, Jerada Province, Oriental Region, Morocco.

Chemical Formula: CaCO3 + Pb
Calcium Carbonate + Lead