Thread: Help id this natural hone!

Backside
21x4.5 cm

Purple brown Stone.green spectacles. Purple slurry

Front side before lapping

Originally Posted by Frameback

Hi Martin,

10 months ago I bough a stone like this from UK in a wooden box, used for chisels in the past.The stone is big. Now finally i took the time to clean it, lap it etc.
Looks excatly the same as yours, and I was suprised to see the green specs on it, it had several. So i searched and digged up this old post. Did you ever find out what type of stone it is and approx grits? I have not tried mine yet but its very very fine, vintage thurigian fine.
Is it a vintage purple YLs or Vosgienne or what was your conculsion?
I am thank.full for any info

My conclusion was that this stone was a yellow lake and not a Vosgienne, but nevertheless after using it for many months now, its a nice finisher.

Thanks Martin, i agree, the same goes for mine

Could be one of the purpleish slate. I have seen them with green spots

Originally Posted by Neil Miller

I would say that the hone is almost certainly a purple slate. These have two types of greenish marks, one is patchy and irregular and the other, depending on the angle of cleavage, is either a well-defined round or squashed oval shape. The source of the stains/dots/spots is due to a ferrous reduction process formed around an original nucleous of iron within the matrix of the slate. Presumably the elliptical dots were once spheres, but the enormous pressure that formed the mudstone into slate has squashed the sphere flat, leaving it as in the following diagram:

Attachment 84250

I have one which shows this elliptical structure perfectly - it has just the one dot in the side of the hone though. Some references state that the dots follow lines diagonally through the hone, like veins.

This name-plate shows the same type of inclusions:

Attachment 84251

As does this gravestone:

Attachment 84252

No - they aren't spots of lichen! They are a bit burnt-out and look white, however.

I don't think that this is confined to welsh purple slate, either. Although I have not seen any I have read of a purple slate from Vermont that has the same type of greenish inclusions, and I suppose that anywhere in the world that slate is found could reproduce the same inclusions under the right conditions.

So, yet again it seems that it is not possible to assign the mine-name and thus the familiar name of the hone to this rock - all we can hazard a guess at is what type of rock it is.

Regards,
Neil

Hi Neil, is there also a Yellow lake variety beeing dark grey/black with a kind of Oval Yellow/Golden dots ? Got this one last week....

Yes, there is, Doorsch. I have had a few, but not with any inclusions, although I think we can accept that all slates may/may not contain inclusions. The dark ones (look quite black when wet) are finer than the purple ones - at least the ones I have had are. I think they are composed of a slightly different type of slate, and therefore harder than usual.

They have a silky feel in use - if lapped well, and remind me of the Cambrock Silkstone a bit.

Regards,
Neil

Originally Posted by Neil Miller

Yes, there is, Doorsch. I have had a few, but not with any inclusions, although I think we can accept that all slates may/may not contain inclusions. The dark ones (look quite black when wet) are finer than the purple ones - at least the ones I have had are. I think they are composed of a slightly different type of slate, and therefore harder than usual.

They have a silky feel in use - if lapped well, and remind me of the Cambrock Silkstone a bit.

Regards,
Neil

HI Neil, thanks for the reply...yes agreed that there might be inclusions or not.....i just thought that there might have been some around with identical colouring in any kind of inclusion. And yes this one is a harder stone then most of the slate i own or owned, so this fits...

I own two Silkstones i will compare honing on these with this one....thanks Neil...