The optical examination of a rock sample in thin section is the quickest and most economical method for classifying rock type and determining which analytical route to follow.

Thin sections for transmitted light are the most common, but there are also:

Polished Thin Sections • Polished sections are used for classification and identification of minerals that cannot be determined in standard thin sections. They are also essential for microprobe analysis. Minute mineral grains are analyzed by bombarding them with a focused bean of electrons, which generate x-rays, characteristic of the elements within the grains. X-rays are identified and quantified to determine the chemical composition of minerals.