What mineral is most like quartz?

Answer 1

Topaz is very much like quartz. They both can be found naturally in any color. They're both harder than glass. Topaz is, however, a little bit harder than quartz and will scratch quartz.

Answer 2

The mineral that is most like quartz is chalcedony. Chalcedony is a type of cryptocrystalline quartz that exhibits similar physical and chemical properties to quartz, such as hardness and transparency.