Assertion: silica's form | /r/MadeOf | heat
Facets:
value: above 250 °c
type: OTHER
Source sentences:
text: Much Amethyst is also heat treated to intensify color, and a green transparent form known as "Green Amethyst" or "Prasiolite" is formed by heat treating certain types of Amethyst.
text: On heating above 250 °C, the completely anhydrous form called β-anhydrite or dead burned plaster is formed.