Minerals Lab

Part A 1. The rate of cooling definitely affects the size of crystals. The crystals that formed on ice formed much faster, and the crystals seemed much smaller. The crystals that cooled on the lab bench cooled much slower, but they appeared much larger. It was hard to identify individual crystals, but the thin rays extending from the centers were much longer in the sample that cooled on the bench, and much shorter in the sample …

…to help us identify an unknown mineral. Next we observed four minerals under plane polarized and cross polarized light, observing the different interference colors that each mineral showed. Using these interference colors, we were able to identify the individual minerals. Lastly, we observed and tested several physical properties of an unknown mineral, including color, luster, transparency, hardness, and streak. We used a computer program to help us identify this mineral based on these physical properties.