Black Rock is not the same as Crowan Beacon. Black Rock is south-west of Crowan Beacon, the other side of the road junction. You can see it quite clearly from the road to Crowan.

On the top of Crowan Beacon there is the rock outcrop which would have been covered by a large cairn. Some of the cairn stones remain in place. This would have been very large, but now has a trig point on top. This hill top has enclosures around it suggesting that it was a Neolithic ritual enclosure. Also on the top, and close to the cairn with the trig point, is a ruined burial mound. Two rings of kerbs are clearly visible and looks as though could once have been a Scillonian entrance tomb, but may have been a bit like Carn Gluze/Ballowal Barrow. However it is very battered. There appear to have been a number of individual burials within the structure.