Question

why some crystals are not coloured ?​

Answer 1

Answer:

Irradiation of pure quartz will cause electrons to be ejected from some of the oxygen atoms. The electrons will return immediately, and the crystal is colorless. The addition of Al to the SiO2 structure (about 1 Al atom for every 10000 Si atoms) results in a change in color in the crystal

Explanation:

Irradiation of pure quartz will cause electrons to be ejected from some of the oxygen atoms. The electrons will return immediately, and the crystal is colorless. The addition of Al to the SiO2 structure (about 1 Al atom for every 10000 Si atoms) results in a change in color in the crystal