Thread: Some natural stone I found.

I found a rock a little while ago (I can't remember where from, but we stuck it in a garden, where it was quickly covered by foliage, I recently re-discovered a large chunk of it), it appears to be similar to shale or slate, I can see lots of small reflections from the rock in the light, and also from the slurry it generates. I'm guessing they're small quartz crystals. I was worried that the reflections may have been from the way I polished the rock, but the slurry has the same reflections (which is a good sign) and dries to a chalky powder (I don't know if this is good or bad or if it doesn't matter).

I cut a piece of it into a rough whetstone to test it on a pocket knife. About 100 laps applying about 1-2 Newtons of force (hey, it's just a SS pocket knife...) gives a shiny edge (I can't tell if it's a mirror finish or not, but it appears to have removed very little steel).

I think I've had enough success with this rock (it does cut steel, and it's definitely >1k) to justify making a proper sized hone from it.

Ask for more information, I can probably find out about it.

Here are some photos of the rock. Click the photos to open full sized images.

No good way to tell from these images....

True it up a bit and try it on some scraps of steel.
Compare it to other known abrasives and sharpening
stones.

The chipped corners seem to expose a coarse and uneven
nature so I am not betting on it being a hone stone -- but
the only way to know is to run some iron and steel over
it.

Not definitive, but not optimistic.

The corner there isn't chipped, I just haven't ground it down that far.