Quartzite is 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. When sandstone is cemented to quartzite, the individual quartz grains recrystallize along with the former cementing material to form an interlocking mosaic of quartz crystals.
Quartzite, in it’s pure form can be harder than granite, but because the quartz is compressed with sandstone and other minerals, there is often variation in the stones hardness. Some quartzites can be harder than granite but some can be soft as marble. Unfortunately to know the true density of the stone you would have to check each individual’s chemical composition, which most quarries don’t have the capabilities to do, due to the rural nature of the business.
All in all there is nothing more beautiful than a quartzite slab, with the colors and beautiful veining. Quartzite is distinctive and a unique stone that is actually interesting.