Glass of possible impact origin from Pica (Chile)

Impact glasses are features associated with many terrestrial impact craters or impact structures that can provide important clues for dating im- pact events or even discovering new impact structures [1]. Also large airbursts have been proposed to be able of melting of the soil surface by radiation [2,3]. Air-busts have been invoked in order to explain the formation of some anomalous silicate glasses like the Libyan Desert Glass. Other examples include Pleisto- cene scoriaceous glasses from Australia [4] and northern Africa. However, as French and Koeberl point out [1], it is often difficult to ascribe an impact origin to such glasses, which closely resemble non-impact glasses such as fulgurites, volcanic glasses or even metallurgical slags. The origin and mechanism of formation of these glasses are thus strongly debated. Hence, proving or disproving the impact origin of these glasses has implications for estimating the flux of airburst producing bolides to the Earth surface.