When studying minerals, a common approach is studying polished thin sections. Also known as petrographic thin sections, these are small, thin sheets of a solid substance ground and polished so that they're ideal for microscopic analysis. There are many types of materials that can be made into thin sections; sample material can range from volcanic sand to prehistoric bone. Crucial to scientific fields such as optical mineralogy and geological chemistry, it's important to know how these polished thin sections are made.
The first step in manufacturing a polished thin section is taking a petrographic sample from its source. Usually from a large deposit, drilled core or hand specimen, the raw sample is cut to billet size for a standard 1x2 inch slide or an oversized 2x3 inch slide. The primary tool for trimming is a diamond saw. Imbedded with shards of pure diamond, this kind of saw is trusted to accurately and safely cut through the sample material (rock) so that edging, and when appropriate the orientation, are maintained.
After cutting and impregnating the material, the sample in billet form is ground to be optically flat and mounted on the glass slide. Then the slide is ground further to the required thickness. A variety of lapping wheels and specialized polishing compounds are used to carefully bring the mounted material to the standard thickness of 30 microns or (30 μm). A polished slide is finished to the industry standard which will vary depending on material type and the type of final analysis being performed.
Now the thin section is ready for petrographic study. Polished thin sections play an integral part in the study of minerals, cement and concrete core analysis, and shale studies for the oil and gas industry. Polished thin sections are commonly used for transmitted light petrography, scanning electron microscopy (SEM), and micro-probe analysis.