Thread: Comparison Sheet for Natural Stones?

Originally Posted by yuzuha

Beryl? Does anyone use beryl as a stone? it is basically emerald or aquamarine and often is found in large hexagonal crystals that are too full of crud or cracks to be of use to anyone exept as a source of beryllium. Wouldn't think it would be worth much as a hone.

Already pointed this out, turns out its good as a polisher according to some. I suspect this is because it was lapped smooth and its harder than steel, so like honing on plate glass.

Originally Posted by yuzuha

...jade...Both can be polished fairly smooth but I don't think they have any set grain size.

Once again, surprisingly its apparently a good polisher. Once again, I suspect it's because it was smooth and harder than steel. Like honing on plate glass.

Originally Posted by yuzuha

Chert is what glues most sandstones and even arkansas stones together. It is basically quartz/silica, the same as agate, jasper, quartzite, opal,flint or novaculite etc. Silica is partially soluble in warm alkaline water and forms flocculant precipitates when the pH goes down. Hydrothermal action often partially dissolves sand (quartzite and sandstone), diatomacious earth (novaculite) and reprecipitates between the grains cementing them together, or silica laden waters dissolve and replace grains of carbonate or other mineral or form a dense cement around impurities (flint, jasper or agate etc). It varies like novaculite... the black stuff is full of manganese dioxide and dense chert cement around heavily dissolved diatom shells (which come in nearly every shape from little 5 micron balls to 200 micron long rods)... in the coarser novaculite stones the shells just less dissolved and not as heavily cemented together.

Tried to make this point, failed.

Originally Posted by yuzuha

It would be pretty much like sharpening on a hunk of plate glass (you could always use ammonium fluoride to etch the surface to whatever degree of "frost" you want)

Also tried this point, apparently doesn't work that way. I suspected this was why the "solid" hones (jade, jasper etc, vs. "particle" hones-sedimentary/metamorphic from sedimentary- coticule, thuringen, japanese naturals, you know the ones every has used for hundreds of years) work- like a steel file: the texture provides the grit, rather than individually sized cutting particles- but I was told I was wrong and not given a reason.

Good thoughts though. You'll find that people are really iffy on the theory here and prefer experience. Even though the "uncommon" materials haven't really been tested enough to have any approximation at normalisation and to determine outliers.