Foinaven is a mountain in Scotland, situated in the northwest corner of the Scottish Highlands. It has a conspicuous white cap of Cambrian quartzite which overlies the ancient Lewisian gneiss basement. This relatively thin quartzite sheet is resistant to normal chemical weathering and erosion, hence the survival of a chain of similar peaks such as neighbouring Arkle and Cranstackie, but is vulnerable to frost shattering, hence the sharp crests around the corries and extensive block fields and scree slopes.