The ability to image crystal habits can be of great utility in identifying phases. The top BEI image shows SnO2 deposited on Al2O3 using PVD with Ar as a carrier gas. EDS determined these structures to all be either Sn or SnOx. SnO2 is a tetragonal system that tends towards prismatic. acicular and botryoidal crystals. Toward the center of the image is what appears to be perfect bipyramids consistent with a tetragonal system. The spherical objects have what appear to be hints of facets. (Thanks to Dr. Peng Xiong, FSU Department of Physics.)
The the bottom SEI image shows a cluster of pyrite pyritohedra-- irregular dodecahedra-- clustered together in a clay mineral sample. The phase identification was immediate upon observation and confirmed using EDS spectroscopy.
(Thanks to Dr. Woody Wise, FSU Department of Earth, Ocean and Atmospheric Science.)