quartz

Quartz is a hard, crystalline mineral which occurs in a wide variety of colors. The grade used in building facades is normally clear or a whitish color.

The clear or whitish varieties are usual in facade work, but the mineral can have other colors. Color is a descriptive characteristic rather than the sole basis for identification.

Quartzite is a separate metamorphic rock formed from sandstone. It is not interchangeable with this mineral designation merely because it contains quartz.