Quartz from Silicified Dyke

If you are unlucky and drill upon this rock below ground level, your diamond bit will be slowly worn of. 
This sample took two days to drill through, so hard that in the end, drilling had to be abandoned. This was encountered near a Bako Village, Kuching.
If you are required to excavate this rock, I think your excavators will rumple. The best is not to touch it, adjust you design level of the building platform or the road level, otherwise move sideway.