This article reviews the life and work of Wilhelm Haidinger, a mineralogist of great importance, who was born two centuries ago. After having worked for ten years with Mohs at Graz and Freiberg Haidinger travelled to Scotland, where he published a "Treatise on Mineralogy". This publication is more than a translation of Mohs "Grundriss der Mineralogie", because it contains a number of corrections and additions. After an interruption in his career as mineralogist, in 1840 he became the successor of Mohs at Vienna. For his students he was an inspiring teacher, moreover he paid much attention to making natural sciences more accessible for the layman. Special subjects of interest were pseudomorphism and pleochroism. He made a first description of quite a number of minerals and gave those a name.