Alfred Des Cloizeaux

Alfred Louis Olivier Legrand Des Cloizeaux was a French mineralogist born October 17, 1817, in Beauvais, Oise, France, who died May 6, 1897, and who conducted systematic research on mineral crystals and their optical properties, including the circular polarization of cinnabar, work he presented in his 1857 doctoral thesis and later in the two-volume Manuel de mineralogie, published between 1862 and 1893. He discovered the potash feldspar mineral microcline, named several minerals including montebrasite in 1871, held professorships at the Ecole Normale Superieure and the Museum National d Histoire Naturelle in Paris, and studied Iceland geysers and the classification of eruptive rocks. He was elected to the French Academy of Sciences in 1869, served as its president in 1889, was elected a member of the American Philosophical Society in 1878, and received the Wollaston Medal in 1886; the mineral descloizite is named in his honor.