What size and type of auger are you using? If it is for soil test boring, there are finger bits available that use square carbide-tipped 'fingers' that are held in sockets and secured by a set screw. They are very effective in hard soil and soft rock.
If you are talking about caisson or foundation augers, they are typically designed with either alloy steel chisel teeth or replaceable button or bullet inserts that have carbide cores surrounded by a softer metal that keeps the carbide from breaking and erodes to permit the carbide to project enough to cut. The chisel teeth will not work in rock and the button teeth don't do much in soil, unless it is very dense and hard.
Auger bit
Re: Auger bit
