Little remains of Black Nab itself which will be completely lost to the sea at some point.
The site below the cliffs is now heavily eroded and covered but its location can be seen on the first edition OS maps.
The most promenant remains are those of a harbour / breakwater below the actual quarry site, the quarry is thought to have been in use between 1649 and 1791.
The highlight is a 1766 datestone which has somehow survived nearly 250 years on the beach.
In the cliff at this location are the ‘Smugglers Holes’ its not really clear whether these actually relate to smuggling, the alum works or possibly jet mining (although my local expert on that tells me they are in the wrong strata)