what is Quartzite?

Quartzite is a very hard metamorphic rock that originated as sandstone. Through a process of high heating and pressurization sandstone is transformed into Quartzite, an extremely strong and durable natural stone. The colors of natural quartzite are generally white or gray with hints of brown and black. When deciding on what to use for your next countertop surface, consider quartzite countertops for its strength, beauty, and overall durability.

Quartzite (from German: Quarzit):

A hard, non-foliated metamorphic rock which was originally pure quartz sandstone. Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts.

Source: https://en.wikipedia.org/wiki/Quartzite