Kerr, P. F. (1931). Optical Mineralogy. McGraw-Hill.
Paul F. Kerr’s "Optical Mineralogy" is a seminal text in geology, offering foundational knowledge on mineral identification through clear descriptions and detailed optical properties. The text remains highly regarded for its systematic approach to microscopy, featuring essential information on birefringence and the optic indicatrix for identifying mineral samples. The 1959 edition is available for viewing on the Internet Archive IUCr Journals Optical mineralogy by P. F. Kerr - IUCr Journals Optical Mineralogy Paul F Kerr.pdf
Optical crystallography and indicatrix
The man was old, with skin like vellum and hands that trembled slightly as he turned a page. Elara approached. He wasn't reading the text. He was just staring at a single plate—Figure 47: “Optic Sign Determination Using the Mica Plate.” Kerr, P