Garnet in other stones than cotticules ?

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Bert2368

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I have been spending some time on learning about the makeup of natural stones and abrasives, which led to brushing up on what little mineralogy and geology I remember. I found the naturals frequently contain some form of Silicon dioxide, others may have silicates such as garnet.

I became interested in finding underexploited/little known/no longer commercially worked mineral resources which might have sharpening performance similar to better known (and usually too expensive for ME to afford!) natural stones- Hence my recent thread on getting a traditional type of Mexican natural stone for testing.

I am finding few references to traditional sources of garnet containing stones other than the yellow and blue Belgian cotticules- Can any point me towards other minerals or deposits of similar makeup which have been used as sharpening stones?

Additionally, does ANYONE make garnet based artificial "water stones", using synthetic garnet crystals in a ceramic, chalk or resin matrix similar to the many Silicon dioxide based water stones? I have not yet found any such.

Synthetic garnet is common for sand blasting grit, sand papers, abrasive boards and cloths. A quick look online shows a lot of sources in many mesh sizes from tens of microns on up to gravel size. The material is available and a couple of natural sharpening stones containing garnet had a good reputation.

Is the apparent tendency to use SiO2 in artificial water stones rather than garnets due to economics or performance? Have I overlooked some other reasons?
 
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Additionally, does ANYONE make garnet based artificial "water stones", using synthetic garnet crystals in a ceramic, chalk or resin matrix similar to the many Silicon dioxide based water stones? I have not yet found any such.

[...]

Wait, are there a bunch of SiO2 waterstones I'm not aware of? Or is that just a slip up and you meant Al2O3?

Looking forward to hear about El Mollejon, btw!
 
Additionally, does ANYONE make garnet based artificial "water stones", using synthetic garnet crystals in a ceramic, chalk or resin matrix similar to the many Silicon dioxide based water stones? I
I'm not aware of any artificial garnet sharpening stones. There are red ruby sharpening stones (aluminium oxide (corundum) with chromium impurities that create the red colour). I've also seen ruby-coated sharpening rods.

But ruby is not the same as garnet, which is a silicate of various metals (magnesium, iron, and others). Even though industrial garnets are used for sandpaper and sandblasting, garnet is not anywhere near as hard as ruby (~7 Mohs vs ~9 Mohs). I suspect that might be why you don't see garnet as a sharpening abrasive. (My guess is that it might be too soft to be effective, but I don't know for certain.)
 
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Yes, I did mean Aluminum oxide in the synthetic water stones rather than the silica in many types of naturals. Need to edit that-

(My all too frequent inaccuracies stem largely from un proof read postings made late at night, often when I can find the time. Not an excuse, just an explanation.)
 
I have found some claims as to natural garnet crystal abrasive giving different sharpening behaviors to the cotticules for different degrees of "wetness" on the surface, due to either the shape of the crstals (faceted, nearly spherical, capable of ROLLING?!) and/or their friability (they are said to break up in use).

I have also seen micro photographic evidence that abrasives in Jnats which were ALSO said to break up in use, etc. NOT breaking up, but rather the clay like binding materials of the natural stones undergoing changes in particle shape.

Natural materials of variable makeup do add another degree of complexity to figuring just what may be going on in a process...

Explanations for what is happening in processes at a level too fine for visual observation based on assumptions may be comforting and even accurately predict an outcome- But just not be correct.

So, what might happen if I got a few samples of micron range garnet crystals, added them to a clay slurry on a flat surface then ran some steel over the mud?
 
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