Why Moldavites are Reduced

Moldavite tektites are colored a bright bottle green by reduced Fe, despite the originating sediments being completely oxidized. The high temperature processing of silicates often results in very reduced products, such as Si-bearing Fe metal in type-1 chondrules [1], lunar regolith agglutinates [2], and multiple Si-Fe metal phases in fulgurites [3,4]. Previous work on silicate reduction has often focused on the need for reducing agents such as carbon or hydrogen; we show that for a moldavite composition these are not necessary. The isentropic cooling path is inherently reducing.