volcanic basalt, workable material, has that dull, mafic metallic-iron look.

could always be quartzite too, but When you said no sandstone in the area, that makes me lean basalt.


basalt is mildly hard, the final edges would grounded sharp. Don’t think it flakes well hence grinding.


basing my hunch of what I can only see in the pic and also off where you found it.