""A Key For The Determination Of Rock-Forming Minerals In Thin Sections"" is a comprehensive guidebook written by Albert Johannsen in 1908. This book is a valuable resource for geologists, mineralogists, and petrologists who are interested in identifying rock-forming minerals in thin sections. The book provides a detailed description of the physical and optical properties of different minerals, along with their crystallographic features. It also includes a series of photomicrographs that illustrate the various mineral structures and textures that can be found in thin sections. The book is divided into two main sections, the first of which covers the identification of minerals in thin sections using polarized light microscopy. This section includes information on the use of polarizing filters, the interpretation of birefringence, and the identification of different types of twinning. The second section covers the identification of minerals using chemical tests and other physical properties. This section includes information on the use of acid tests, hardness tests, and specific gravity measurements, among others. Overall, ""A Key For The Determination Of Rock-Forming Minerals In Thin Sections"" is a valuable resource for anyone interested in the study of rocks and minerals. It provides a comprehensive overview of the properties and characteristics of different minerals, along with practical guidance on how to identify them in thin sections. The book is written in a clear and concise style, making it accessible to both students and professionals in the field of geology.This scarce antiquarian book is a facsimile reprint of the old original and may contain some imperfections such as library marks and notations. Because we believe this work is culturally important, we have made it available as part of our commitment for protecting, preserving, and promoting the world's literature in affordable, high quality, modern editions, that are true to their original work.