In many parts of Northern Scandinavia there was a shift in raw material use during the Late Mesolithic, with the comparably soft rock-type slate starting to play an increasing role in the lithic industries. This is especially evident in Northern Norway where slate to a large degree replaced hard rock types like chert and quartz in the local industries. Slate is soft and brittle, but has the advantage that it can be shaped into knives and points with evens shapes through grinding and polishing. The design of for example knives and arrowheads of slate, are therefore more akin to bone-tools, than to other stone tools, sometimes with intrinsic designs and carved decoration. Despite the fact that slate tools dominate many Stone Age assemblages in Northern Norway, there have been little research done on these type of implements. This paper focus on knives of slate from Finnmark and northern Troms in Northern Norway, and discuss problems of typology, chronology, and practical use, as well as raw-material variability assessed by the use of pXRF.