The lighter colored rock is a magmatic intrusion of predominantly quartz layered in between the gneissic schist. Sometimes people confuse this rock with granite. The rock in the Black is gnessic schist, which is granitic is nature but different. The intrusions are from ancient magma flows. I could go on, but I haven't really started geology class yet.
I'm thinking sodium plagioclase feldspar more than quartz and the pinker ones are potasium orthoclase feldspar...i.e. "pegmatite". There probably is quartz in there, but I'm thinking it's not the majority component...could be wrong as I've certainly never been on that pitch, but I've looked at it from afar many times.