Here's a chisel made of argillite, probably by the Haida of the NW coast as I found it on a beach in what were then called the Queen Charlotte islands (now Haida Gwai):
Argillite is a very soft slate--lightly metamorphosed mudstone. It was popular (and still is) with the NW coast folks for tools and carvings. This chisel has been rounded from a century or so of rolling around in the surf, but still shows the distinctive form of the NW coast abraded chisels.
The Haida were famous for their ocean-going giant canoes and probably their best-known invention, the Haida bed
