I know table salt is white, but that is because you have power and you have multiple surfaces scattering, but a large crystal of sodium chloride is clear and colorless.

我知道食用盐是白色的，但这是因为你让它成了粉末,因为有了多个散射面，但是一个大的氯化钠晶体,是无色透明的。

麻省理工公开课 - 固态化学导论课程节选