Trinitite image (c) 2003 Andrew Alden, licensed to About.com, Inc. (fair use policy)
Trinity was the name of the first atomic bomb test, on 16 July 1945, in a desolate desert valley in New Mexico between Socorro and Alamogordo. The explosion created an expanse of sandy desert ground covered with glass, later dubbed "trinitite." This trinitite specimen is a small piece of it, a tangible reminder of what we have wrought. It is mostly melted quartz with traces of olivine and feldspar. The radioactivity it once had is now negligible (see an analysis of trinitite's radiation).
The trinitite appears to have formed as sand was sucked up into the nuclear fireball and fell back in a rain of molten glass, according to a new theory. It was always assumed that trinitite formed on the ground under the fireball's direct glare, but science thrives by revisiting assumptions in the search for truer explanations.
The test site is a National Historic Landmark, closed to visitors except for two days a year: the first Saturdays of April and October.
Trinitite was once cheap enough to be offered in the Edmunds Scientific catalog, which is how I acquired this piece in the 1960s. It is a sobering curiosity.
Little trinitite is left at Trinity, and collecting is no longer allowed. The story of trinitite is reminiscent of the famous solid crusts of horn silver that dotted Nevada in the 1860s Silver Rush.