thermochromic crystal

_… + 12NH₄Cl Tetrasulfur tetranitride forms thermochromic crystals, which are crystals that change colour with temperature. They are red at temperatures above 100 °C (210 °F), orange at 25 °C (80 °F), and colourless at −190 °C (−310 °F). The crystals are stable in air but will explode in response to…