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The results suggest the writing surface is largely composed of sulfate salts, including glauberite, gypsum and thenardite – minerals that dissolve in water and are left behind when the water evaporates.

As the mineral thenardite or mirabilite, which crystallizes in the rhombic system, it occurs in many parts of the world, as in Spain, the western states of North America and the Russian Caucasus; in the last-named region, about 25 m.

Thenardite is an edible mineral used in the production of machines, glasses, paper and other industrial products.