QUARTZITE

Quartzite is a metamorphic rock formed when quartz sands are subjected to extreme heat and pressure due to tectonic forces. Pure quartzite is white. The individual quartz crystals are generally visible.

Like a marble, color and patterns in quartzite are the result of impurities. Quartzite is very hard (unlike a marble), and is not water soluble. Being thus resistant to weathering, it often forms ridges and hilltops.