Trinitite - "16 July 1945, the first atomic bomb was detonated in an isolated area of the New Mexico desert, code named Trinity. The Trinity test was conducted near Alamogordo, Socorro County, in the Tularosa Basin, New Mexico."

"A product resulting from the blast was an olive-green glass-like substance named "Trinitite" (a nearly pure melted silica with traces of Olivine, Feldspar, and other minerals mixed in the desert sand) which formed when the molten sand solidified upon cooling." quoted from Schoolers mineral dealers website.

These small specimens were obtained in the early 50's.