Grind stones that are circular in shape, made of stone and have a square hole for the shaft in the middle are common - I can show you a photo of the one built into my front wall if you want !
The stone here is however rounded on the sides and not just worn down on the flat outer edge
My assumption is that they were generally used to sharpen tools against the flat edge so would wear down uniformly.
The earliest image of a grindstone in use is supposed to be (according to wikipedia!!) in the Utrecht Psalter and that shows one being used in the way I describe
(see https://en.wikipedia.org/wiki/Utrecht_Psalter#/media/File:Utrecht_Ps63_(cropped)_(cropped2).jpg)
From a mining perspective however since tools are being sharpened to a point (i.e. picks) rather than for a cutting edge (e.d. swords, scythes etc) it is possible they would use surface differently and the stone would get rounded on the sides as well
I am however not aware of any other evidence of this from other tools at other sites
Regards
David
On 6 Nov 2015, at 12:48, Mike Worsfold <[log in to unmask]> wrote:
> I don't see why a square hole means that it was designed to rotate. Unless you are drilling a hole with a rotating tool, it is as easy to make a square hole as a round one. It could be a simple weight, say a counter-weight on a beam.
>
> Is it soft stone? I suppose you don't want to test that. Even if hard now, it could have been soft when first exposed.
> Mike Worsfold
>
> On 05/11/2015 20:01, Martin Critchley wrote:
>> I've been sent a photograph of some objects which were discovered at Avoca, Ireland by one of the mining engineers in the early 1980's. The pick, hammer and clog sole are obvious but we have not seen anything like the circular object before. The object is made of local stone and appears to have a wooden shaft with either a metal or wooden pin (looks a bit like Fred Flintstone's wheel to me!). Any suggestions would be welcome.
>>
>> The photo is on the following link: http://www.era.ie/mhti_pics/avoca_objects.jpg
>>
>> Martin
>>
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