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Published January 1949 | public
Journal Article

Grain-thin sections and other teaching aids in optical mineralogy

Abstract

In an effort to make it possible for a student in optical mineralogy to study all of the optical characteristics of a mineral in a thin section, a method has been developed for making thin sections containing an ample number of grains of the same mineral in random orientations, in which each individual grain is completely surrounded by Canada balsam. The materials commonly used in the optical mineralogy laboratory for studying the optical properties of one particular mineral usually consist of: (1) mineral grains or powder between 150 and 200 mesh for the immersion method, (2) slides containing these grains, mounted in Canada balsam, (3) a set of thin sections of a large piece of mineral at random orientation, usually showing only one orientation, (4) thin sections of rock, containing among other minerals some grains of the mineral under consideration, and (5) oriented slides containing one small piece of mineral at one special orientation.

Additional Information

© 1949 Mineralogical Society of America. The author expresses thanks for their kind help and interest to: Dr. Ian Campbell of the California Institute of Technology for encouraging the development of these slides in the thin-section laboratory, for his valuable suggestions and interest in the work, and criticism while the work was in progress; to Dr. George Tunell for contributing helpful suggestions and much encouragement, and for reading the manuscript; to Dr. R. H. Jahns, who contributed the suggestion for the Bx_a-Bx_o slide and a supply of 40° muscovite with constant optic axis angle in the different cleavage lamellae; to Dr. Clay T. Smith, who suggested the optic axis angle slide and showed much interest in the progress of the work; to Dr. Wyatt Durham, who recommended the use of salt water for dissolving gypsum.

Additional details

Created:
August 19, 2023
Modified:
October 23, 2023