Viking Sun Compass stone?

the following URL displays a photo of the soapstone found at Vatnahverfi, Greenland. It has been thought that the curve above the hole is a so-called gnomon curve. If that is so, then the stone may have been used as a solar compass. For that purpose the stone needs to be positioned horisontally, and a vertical pointer (i.e. a "gnomon") of the right length needs to be inserted through the hole. The stone then has to be rotateded until the shadow of the tip of the gnomon falls on the curve. The stone will then show North. The use of such a device requires fair weather (shadows) and a quiet sea. It has been debated whether it could indeed be such a solar compass that we have here, or whether the curve has some other significance. Note that soapstone (kleberstein) is soft enough to be cut with a knife (has any one tried?). Also note that different curves are needed for different dates as well as latitudes. From:

Deze "vondst" kan nep zijn. Op de vikingsite van de veramerikaanste Sjolanderfamilie ( -vikingnazaten- kun je veel "fake" vondsten vinden (dat vinden ze zelf natuurlijk niet).