Finitite

Finitite is a glassy material produced when the intense heat of a nuclear explosion melts the surrounding rock or sand and the molten mix then rapidly cools into a brittle, glass-like crust and interior fragments. The term is used for post-detonation glass at various sites; the specific glass from the Trinity test is often called trinitite, while the general phenomenon on other test sites is referred to as finitite.

Formation occurs when ground materials near the detonation are heated above their melting points, causing fusion of minerals such as quartz and feldspar. The molten layer can flow and pool around the crater, then quench into glass as it contacts cooler air and soil. The resulting pieces can range from crust-like sheets to angular shards embedded in the fused substrate. The exact texture and color depend on local geology and the presence of metal or other additives.

Composition and appearance vary widely. Finitite typically consists of fused silica and silicate minerals, with possible inclusions of metallic fragments from the device, such as copper or aluminum from the bomb casing. Colors can range from pale green to brown, influenced by impurities, mineral content, and irradiation history. In some locales, the material also contains trace amounts of fission and activation products, giving a low level of radioactivity.

Finitite has historical and scientific significance as a material record of a nuclear explosion. It provides clues about the energy release, detonation environment, and local geology. It remains primarily of interest to researchers and collectors, with handling typically subject to radiological safety considerations.