1768-1851

British geologist best known for inventing the Nicol prism for studying rocks and minerals under polarized light. The Nicol prism, still in widespread use today, made possible the use of petrographic microscopes for the study of sections of rock ground to near-transparency. This opened the door for the identification of small mineral grains and textures in rocks. Such knowledge gave new insights into the manner in which rocks, minerals, and large geologic features formed.