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Thanks Brett for your interest. I believe that the glass can't be volcanic in origin because my colleagues at Johnson Mathey and Queen Mary University of London have shown that it is almost pure silica glass, with no temperature-lowering minerals, and a melting temperature in excess of 1,600C. The temperature of magma lies between 600 and 1,300C. Obsidian (volcanic glass), which is formed when felsic magma cools too rapidly to crystallise, is usually dark in colour, and around 70% silica. Although Shui Jing glass varies in colour, much of it is colourless, and even where streaked, for example with red streaks (which are due to iron, potassium, aluminium and sodium, which all co-locate), the background is pure silica. So it must have formed well in excess of 1,600 C, and since the boiling point is 2,230 C I suspect at much higher temperatures. Temperatures at the moment of a giant meteor impact are higher than anything else on earth - 25,000 C plus.