How to tag monadnocks?

How to properly tag small rock formations, like ?

Seems that natural=stone is a more common tag than landmark=large_rock.

landmark=rock_pinnacle, maybe? At the moment there’s just one object carrying that tag in OSM.

Your third example looks a bit like what the South Africans would call a “Castle Kopje”. I’ve used “natural=castle_kopje” for one of those in Derbyshire, but it’s the only one in Taginfo. Despite being English I’ve no idea what the native English term for something like this would be.