What are the differences between the various types of thin sections, and what are they each used for?
A Standard thin section is a 30 µm-thick slice of rock, concrete, etc., mounted with epoxy onto a 27 × 46 mm glass slide. Using a grinding process involving flat, horizontal wheels (called lapping), we finish standard thin sections with 600-mesh (extra-fine) silicon carbide abrasive and fit them with thin glass coverslips. This type of thin section is best suited for routine petrography. We are able to process the surface of a lapped thin section with a series of progressively finer polishing compounds to produce a polished thin section which has a scratch-free, highly reflective surface. Polished thin sections can be used for electron microprobe or SEM analysis, or to identify by reflected-light petrography the various kinds of opaque, metallic minerals present in most rocks. Because these types of analyses require direct access to the sample surface, polished thin sections are not coverslipped. Polished ore sections are ±1 mm thick, polished plates mounted on standard 27 × 46 mm slid
