In the next farm along from Hillhead of Crantit a perforated macehead was found at Musterquoy {http://www.huntsearch.gla.ac.uk/cgi-bin/foxweb/huntsearch/DetailedResults.fwx?collection=all&SearchTerm=B.1914.643&mdaCode=GLAHM&reqMethod=Link&browseMode=on} so perhaps I have to take back what I said about Hillhead of Crantit not being the source of a stone ball.
Close by Hillhead of Crantit is Highland Park Distillery, where a microlith turned up whilst digging foundations some fifty years before 1986 - what later became the Meadow of Scapa was a freshwater loch in the Mesolithic. Can one dare hope that plans for new housing on the still damp brae (wonderful yellow flag flowers every abundantly summer) reveals faint traces or summat.
The 1882 map shows two Hillheads. The second, just before you come to Highland Park Distillery, is no longer extant. It was called Hillhead of Crantit (HY45090927). HY40NW 13 places two balls recovered here (though confusingly also naming it Hillhead House, which is simply Hillhead) The other side of the house boundary, at HY45090924, was a minor earthwork. Could this be the location of the 'actual' Crantit Souterrain?
RCAHMS NMRS No. HY40NW 6 at HY44720855.
1882 A large circular mound, uncultivatable because of stones.
1993 Fort. Spread over two fields (mostly that called 'Well Park'), with many features lost to levelling i.e. no trace of entrance. Single earthen rampart encloses oval area roughly 75 yards north-south by 55 yards [boundary features uphill and downhill lost since 1882 ?].
1964 Enclosure. Now being ploughed out, the site on a western slope has a smaller earth bank inside the main one.
Of the carved stone balls found in Orkney a quarter came from this hillside. One of sandstone from this actual site was last seen in a collection (NMAS, HH417). Of two at HY40NW 13 one is in the Hunterian Museum (B.1914.356) whilst the whereabouts of one of diorite from Hillswick in Shetland are not known. Another was discovered by 1882 drain diggings in 'Well Park' a couple of yards from where a well/spring existed until a decade before (HY40NW 12 located at HY44730866 on the present well [though a dark triangle visible from the road below seems a likely issuance to me] ).
If these balls are truly associated with this site that would put it back at least as far as the Bronze Age. On the other hand, on the basis of the little I know presently, an archaeologist friend is inclined to put it much later and relates it to pre-broch Clickhimin or possibly The Howe 3/4 (even amorphous post-broch).
When I attended a talk on the Bu of Orphir it was revealed that geophysics in Orphir had shown a double ring of 70m diameter. If this site were originally more circular the dimensions are comparable - could there be a connection?
Go out of town on the South Isles road past the Highland Park distillery and before reaching the Tradespark junction enter the field on the downhill side of the road opposite. Cut diagonally across this to the gap at the corner behind Hillhead (of Scapa) House.
Striking off right downhill on another diagonal takes you to the site of the long-gone well in front of whose vanished place a decorated stone ball was found almost as long ago. You have to wonder what yet remained to mark it out - was it demolished ruins or simply (like Crossiecrown) filled in with rubble ? Could it be that the 'new' well of 20th century vintage does occupy the self-same site hidden from view. Unfortunately this has an airtight seal at the top of the circular concrete 'plug', overlying a symmetric well of drystane walling the same diameter. In the same hollow the hut has been removed to expose the concrete foundation below (hopefully nothing destructive is intended for this place). Connecting this and the well are flags that go under the former hut's foundation. About the modern constructions lie many stones of older times, but are they from here or brought in from elsewhere? One I am struck by is a dark slab with a rectangular section out of one corner that reminds me of a re-usable form of cist. The exposed section of hollow above the modern stuff seems curiously empty (like bared parts of the enclosure), only a few protruding stones with an earthfast boulder at the back of curious colouration.
Looking across the hill with your back to Kirkwall you can see the nearby enclosure, once considered a fort by those who saw it a little better than we. Standing a little above the well hollow provides the best view of the Hillhead site's profile, better detail at least than that of the half below the house. Is one looking at two banks and a ditch or a bank and two ditches, no-one is totally convincing and if any excavation was done it was way back and very slight.
Near the drystane wall you are conscious of a wide flattened section on either side that goes downhill without seeming to break the enclosure otherwise. One assumes that this came about when the original Well Park was divided up, and further that material from the enclosure would have been robbed to form the wall itself. To see the other half of the site you have to go back up beside the wall to the house and down into next field. It appears to be a smaller 'half', and as mentioned before presents a much less detailed appearance. Also there are only a couple of bared areas. Similar to the bank/ditch dichotomy we cannot tell if the relative 'smoothness' represents more of the original form surviving or, conversely, the greater subsequent subjection to the hand of man.
I wonder if the Hillhead of Crantit was a similar site to Hillhead - between that tidgy hollow the old O.S. miscalls a quarry and the distillery there is a curve to the hill that looks suspiciously regular and the earthwork at the ruined steading's uphill side could be where a bank has been cut by the road ?