petrosilex

plural petrosilexes

1. chemistryfelsite

   Petrosilex has given rise to different .

   1871, Thomas Egleston, Catalogue of Minerals, with Their Formulae and Crystalline Systems

   2 more examples

   The name simple petrosilex seems to have been confined to the more apparenttly homogeneous felsites, while the term porphyritic petrosilex was given to those rocks supposed to have a base of simple petrosilex or of felsparoid which held enclosed porphyritic crystals.

   1884, Harvard University. Museum of Comparative Zoology, Bulletin: Geological series - Volume 1, page 399

   A brief history of the word felsite and its synonyms in different countries (petrosilex, eurite, and ha:lleflinta) will serve to illustrate the unfitness of it and these allied terms for exact petrographical usage.

   1896, Arthur Winslow, Charles Doolittle Walcott, Florence Bascom, Contributions to the Cretaceous Paleontology of the Pacific

2. chemistryA fine-grained, silica-rich rock composed of quartz and sometimes other minerals, similar to the chemical structure of hornstone but having a different texture.