Chert is a very fine grained rock formed in ancient ocean sediments. It often has a semi_glassy finish and is usually white, pinkish, brown, grey, or blue_grey in color. It can be shaped into arrowheads by chipping. It has often been called flint, but true flint is found in chalk deposits and is a distinctive blackish color.
ie. it's hard. Good luck with those drill bits. I have found no matter how hard the rock, the more powerful your drill the better the result. Get hold of at least 24v but preferably use a Hilti 36volt with some fresh bits.