Thread: Slate backed German yellow razor stones?

In a Dictionary of Arts, Manufactures and Mines from 1867 the following entry is made in describing a German razor hone:


"The German razor hone has long been celebrated. It is obtained in the slate mountains in the neighborhood of Ratisbon, where it occurs in the form of a yellow vein running through the blue slate, varying in thickness from 1 to 18 inches. When quarried it is sawn into thin slabs, and these are generally cemented to slices of slate which serve as a support. Sometimes, however, the yellow and the blue slate are cut out naturally combined."

Does anyone have what they think is a coticule bonded to a BBW base, but the base doesn't look like BBW?

The description above doesn't IMO describe a Yellow Escher type stone.

I'm very intrigued by this.

Chris L

Here's an excerpt from "The Non-Metallic Minerals: Their Occurrence and Uses"
By George Merrill

According to Renard,1 the celebrated Belgian razor hone quarried at
Lierreux, Sart, Salm-Chateau, Bihau, and Recht is a damourite slate
containing innumerable garnets, more than 100,000 in a cubic millimeter.
Like the Ratisbon hone, this occurs in the form of thin, yellowish bands,
some 6 centimeters wide (2§ inches) in a blue-gray slate (phyllade).
The bands are essentially parallel with one another and with the grain of
the slate, into which they at times gradually merge. The chemical composition
of a sample from Recht is given on the next page.

Definitely not an escher type. It sounds like it's almost identical to coti. Perhaps the ones that are swimming around that aren't labeled German are just assumed to be cotis?

( I should note that the book also has a microscopic image of the Ratisbon showing garnets on the surface, so it appears they are refering to both ratisbon and belgian when they describe the properties in the exerpt above It in fact mentions that the "microscopic structure of the stone as described and figured is essentially the same as the Ratisbon")

See also this interesting thread, and this one.

It seems entirely possible there could be another grade of Escher/thuringian hone out there. The colors I have seen run from blue-black all the way to light green-yellow... Why couldn't there be a super rare vein of "pure yellow" as well?

It seems hard to believe that anybody could confuse a coticule with an Escher type stone. They feel completely different in use, and the folks in the "old days" (even without benefit of forums like this), had to have been able to tell the difference. I dunno.

Originally Posted by ChrisL

In a Dictionary of Arts, Manufactures and Mines from 1867 the following entry is made in describing a German razor hone:


"The German razor hone has long been celebrated. It is obtained in the slate mountains in the neighborhood of Ratisbon, where it occurs in the form of a yellow vein running through the blue slate, varying in thickness from 1 to 18 inches. When quarried it is sawn into thin slabs, and these are generally cemented to slices of slate which serve as a support. Sometimes, however, the yellow and the blue slate are cut out naturally combined."

Does anyone have what they think is a coticule bonded to a BBW base, but the base doesn't look like BBW?

The description above doesn't IMO describe a Yellow Escher type stone.

I'm very intrigued by this.

Chris L

What I find interesting is that, if I understand the history correctly, the bbw, or in the case the Ratisbon 'blue slate', was not known to be a sharpening medium until recently. Wasn't it used for reinforcing the yellow and for paving stones and such ?

My two 'Old Rock' natural yellow/bbw Belgian coticules have a glued label completely covering the blue side. Obviously when they marketed those they didn't plan on the bbw being used for sharpening.

I'm wondering if the 'blue slate' in the description of the Ratisbon 'coticule' is equivalent to the bbw we know and love ?

Could these stones also be the culprit for the difference in vintage and newer coticules? maybe the yellow German coticule looking thing is finer and thus some stones thought to be coticules are the ones with the finer edge making characteristics which are German.. Damn... I can feel my HAD running through my veins now... Again.

I think there's a simple explanation for this.
Before WW1 that part of Belgium belonged to Germany.
'Recht' still is a German speaking village but is part of Belgium since approx. 1920.

Isn't Ratisbon in SE Germany though? There may be old Coticules from Recht labeled as German hones, but I'd think it must be a seperate issue from these stones as they are stated as being mined in and around Ratisbon?

I recall Howard Schechter had said that there are coticule veins in the U.S. in the New England area. IIRC he said the veins do not run in such a way to have been feasible for mining.

Could the German yellow hone which apparently was garnet based in its abrasive qualities simply be a coticule but from a different area than the Belgian coticule?

Chris L

Is anyone able to explain the inner workings of geological marvels and mysteries to us the obtuse? Such as: what got melted to get squirted into finer cooler rock strata to form the coticule that we now all love, cherish, and covet?

I suspect that if this material, which I'll betcha is older volcanic ash, got remelted and squeezed into older colder rock fissures, would probably have very similar characteristics whether the heated squeeze occured in Germany, Belgium, or Vermont.

Then again, about all I know of rocks is that they are heavy and hurt when you drop one on your foot.