Quartzite is a metamorphic rock, meaning that it was formed from a prior rock, which was modified by heat, pressure or both. It was formed from a pure, white sandstone, which was almost entirely quartz, subjected to heat and pressure, which fused the quartz grains. The purplish-reddish colour has to do with Iron formation due to oxygen buildup during the Huronian, with the largest amount present at the top.
Here we are with the crane picking up the Purple Quartzite and its sister rock (rock with glacial striae in the garden). The other rock is the first we collected - Jasper Conglomerate. Sam Vales is directing the crane operation.