There are 'two huge granite boulders, situated on a shelving rock over an abyss on the Loch Avon side of Cairngorm, with hand-made cups on them about a foot wide and correspondingly deep - "sitting on which is said to be efficaceous in cases of barrenness" '. Pilgrimages have been made to them within living memory.
A Mitchell 1875.
Mitchell and Drummond, A and J (1875) 'Vacation notes in Cromar, Burghead, and Strathspey. Including notice of one of the supposed burial-places of St Columba', Proc Soc Antiq Scot, vol.10