Quartzite

Quartzite is a hard, non-foliated metamorphic rock that was originally pure quartz sandstone. Sandstone converted into quartzite through heating and pressure usually related to tectonic compression. Pure quartzite is usually white to grey, though quartzites often occur in various shades of pink and red due to varying amounts of hematite. Other colors, such as yellow, green, blue and orange, are due to other minerals.

The term also sometimes used for very hard but unmetamorphosed sandstones that composed of quartz grains thoroughly cemented with additional quartz.

It is very resistant to chemical weathering and often forms ridges and resistant hilltops. The nearly pure silica content of the rock provides little material for soil.