Forty-Seventh Rochester Mineralogical Symposium: Contributed Papers in Specimen Mineralogy—Part 3.

PHOTO (COLOR): RMS Program Cover by Susan Robinson THE THIRTY-SEVENTH TECHNICAL SESSION of the Rochester Mineralogical Symposium was cancelled this year due to the COVID-19 virus. By experimenting with the addition of mica of varying thickness to the optical path when viewing a flattened gahnite and garnet in crossed polars, we found that the observed interference figure was the result of the mica even when exceedingly thin. Multiple flattened almandine crystals have also been extracted from muscovite books from Avondale, Pennsylvania. White included the results of optical analyses performed by our research group on a flattened gahnite, which showed that the crystal exhibited a distinctly biaxial interference figure despite being an isometric mineral. [Extracted from the article]