Natural glass such as obsidian is formed by heat and pressure in volcanic sites, however there are other naturally occurring glasses that are formed by other means. Tektite refers to a class of naturally occurring glasses that are ejected from meteor impacts as the intense heat and pressure melts and scatters the surrounding rock. While obsidian occurs mostly in black and dark shades, tektite occurs in pale green and yellow. Moldavite, for example, is a beautiful forest green variety found in the Moldau river in Czechoslovakia. Aside from its aesthetic value, scientists are currently investigating tektites as a clue to previous extinction events in the Earth’s history, as many samples contain datable radiation leftover from the impact.
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