thin section

plural thin sections

1. chemistryA thin, optically flat sliver of a material, especially a rock or mineral, that can be used in microscopy.

   The purpose of this book is to illustrate the appearance of many of the common rock-forming minerals in thin section under the microscope.

   1980, W. S. Mackenzie, C. Guilford, Atlas of rock-forming minerals in thin section, page iv

   1 more example

   Before long, as Dawson (1992) pointed out, Sorby (1863) also made thin sections of some of the fused charges of basalt produced by Sir James Hall.

   2003, Davis Young, Mind over Magma: The Story of Igneous Petrology, page 150

2. Used other than figuratively or idiomatically: see thin, section.