Hammondville Quartz Albite Zircon

Zircon grains from a quartz-albite rock in Hammondville, NY. The grains were hand-picked from the rock, embedded in epoxy, ground to about half-thickness, and polished. Left: petrographic microscope transmitted light image showing cracks, inclusions, and age “zones” throughout the grains. Right: SEM (scanning electron microprobe) cathodoluminescence showing zones with different trace element compositions, which, in this case, correspond to differences in age. The cores and rims of the zircon grain reflect magmatic and tectonic events that occurred within the region about 1-1.15 billion years ago. Images by John Aleinikoff, USGS.