It Depends(tm). Usually on the grain alignment/lack thereof. As long as the grains are suitably randomized, it can be very durable. [https://en.m.wikipedia.org/

It Depends(tm). Usually on the grain alignment/lack thereof. As long as the grains are suitably randomized, it can be very durable. [https://en.m.wikipedia.org/wiki/Quartzite https://en.m.wikipedia.org/wiki/Quartzite]