Several years ago, one of our grad student customers performed an informal survey and sent duplicate sets of ore samples to "several reputable thin section makers" and to a university facility in China. "I specifically chose difficult samples to polish", he wrote. For the benifit of his fellow students, he summarized the results in poster form, which included several reflected-light images for comparison purposes. He was kind enough to share a few copies of these photomicrographs with us, along with his comments.

The image below on the left is one of our polished thin sections. It is one of the ore samples included in the survey set from the Magma Mine in Superior, Arizona. Minerals present in this view (and the other photos) are bornite (purplish-tan), chalcopyrite (yellow), pyrite (white), and quartz (gray). Voids and pits appear black. "...[in the Burnham section] mineral boundaries are clearly visible and mineral identification is straight-forward. Minor phases such as the silver hematite grains in some of the smallest veins are obvious. Pyrite not scratched. Appropriate amount of relief (i.e. minimal)."

Compare our section on the left to that of a competitor’s on the right: