Local natural stones

[fishfinder401]

First off, sorry if this is the wrong section of the forum to ask this but it seemed most fitting.

 

So, on to my question/ idea.... I have been tempted recently to try to make my own sharpening stones from local stone in my town or the area around it. While im not under the impression ill find some super amazing stone that will replace my tried and true ones I currently use, what should I look for to have a chance at a useable stone? 

And if it helps, I am in southern rhode island.

 

 

[ThomasPowers]

What did people in your area historically use?  You may do better asking at a local University's Geology department; I'd check out quartzites and siliceous schists over granites and gneisses.  

[fishfinder401]

that is actually a really good idea, ill see who at their geology dept. i can find. and i definitely know there are some big veins of some type/types of quartz, and also types of what i think is a form of shale? (its dark, seems pretty consistent texture and seems to be sedimentary to some level because of the obvious levels

[ThomasPowers]

Historically sandstones and things like novaculite were used a lot; but getting just the right wear vs sharpening can be tricky.  In cities you could sometimes see that one townhouse had a stone on their stoop that worked just right and folks from all over the neighborhood would use it to sharpen their kitchen knives.  A big problem is that some of the modern Knife alloys are too hard for most natural stones, some even require diamond hones to sharpen them efficiently.

In Columbus Ohio there is still "Whetstone Park" where an outcrop provided appropriate stones.  (IIRC there is a chapter about whetstones in one of the Wood Wright's book---ahh yes "The Woodwright's Companion" has a section on "the search for the whetstone quarry".)

[fishfinder401]

wow that's really interesting about the stoop haha i had never heard that

Well I found a small rock in ky yard that loiks worthy of experimenting on... Surprisingly fine grit it seems, slow cutting though

 

[ThomasPowers]

You can see examples with the shallow dip along the top on the side.  Distinctive wear pattern.

I'll have to go through my 100+ year old Sears Roebuck Catalog reprints and see what they were selling in the 1890's and early 1900's.

[Glenn]

Your grandmother would rub the kitchen knife along the top edge of the crock pot to dress up the edge of her knife.  Now days they sell round rods called crock sticks for the same purpose.

[George N. M.]

Dear FF:  You will need something harder than the steel you are sharpening.  Generally, shale would be too soft.  Sandstones of various types would possibly work depending on how tightly the quartz grains (which are harder than steel) are cemented to each other.  The rock you found in your yard appears to be a slate or schist which may be hard enough.

You have to decide what, exactly, you are doing.  Are you trying to remove steel to create an edge or are you polishing the edge to align the little bits of steel along the existing edge.  This is the difference between use of coarse and fine commercial stones.  Natural stones follow the same pattern of use. 

"By hammer and hand all arts do stand."

[Kozzy]

 

Might be possible. Found a single reference from a USGS publication that mentioned whetstones being made in Woonsocket RI.

"Other Rocks

Only minor use for dimension stone has been made of such rocks as marble and Pennsylvanian sandstone. Very minor use has been made of soapstone in lenses of the Blackstone Series. The sandstone at Woonsocket was used for making "ten thousand dozen" whetstones in 1840 (Jackson, 1840, p. 71)."

From "Bedrock Geology of Rhode Island"  https://pubs.usgs.gov/bul/1295/report.pdf

[fishfinder401]

1 hour ago, George N. M. said:

Dear FF:  You will need something harder than the steel you are sharpening

Yeah whatever the stone I played with today is is on the softer side but seems just hard enough to lightly abrade the surface but closer to a polishing stone.

Also i should say these wont be replacing my current sharpening stone setup, but unless I find something that works better it is more of a curiosity 

1 hour ago, Kozzy said:

Might be possible. Found a single reference from a USGS publication that mentioned whetstones being made in Woonsocket RI.

oh that is very interesting... Ill have to look into that

[fishfinder401]

So, found another rock that split nice and flat that seems to have a pretty consistent grain to it, but unlike the last one this is much much harder... 

[fishfinder401]

after so searching of geological data this seems to me to most likely be 

Graywacke

...a dark gray, firmly indurated, coarse-grained sandstone that consists of poorly sorted angular to subangular grains of quartz and feldspar, with a variety of dark rock and mineral fragments embedded in a compact clayey matrix having the general composition of slate and containing an abundance of very fine-grained illite, sericite, and chloritic minerals.

This category is also used for graywache.

[Frosty]

Graywake? I suppose if you can find a lens with clear enough bedding plane you can split it and maintain a useful surface. 

Arkansas stones are a particularly high grade novaculite, There is a good description of the stones, various grades, how and why they work on the Arkansas sharpening stone site. 

You could contact the local rock club AKA "Gem and Mineral Society," and find out what's available locally and if you're a personable guy on the phone maybe someone will have something they'd be willing to cut you a suitable piece. Offering to swap for a custom hand forged rock hammer or pry bar wouldn't hurt. I used a maybe 10" pry bar and a speed bar fossil hunting, they let you separate lenses without potentially damaging fossils with a hammer blow.

Frosty The Lucky.

[fishfinder401]

i got lucky that the piece I found was a nice flat piece that split off but the face needs a little flattening to get to sharpening stone flatness, i also have a piece about twice this size also pretty flat that i split this piece from so it it has any good use for me, i may have a nice large stone to play with in the end. and that is my guess on the type though based on description, pictures and the fact that it is a primary rock type in the formation this land is on.

I plan on contacting my local group this week to see what knowledge and resources they would be willing to share or trade for, the more i look into this the more fascinated i am getting with geology haha

[George N. M.]

Graywacke is basically "dirty" sandstone and if it is "poorly sorted" that means that there are big and small grains present.  That would make for a poor whetstone because the big grains, assuming they are quartz, would gouge the steel and the smaller grains would have little effect.  What you want is a uniformly sorted, well cemented sandstone.  If you can find different sized grits for different stones fr different sharpening tasks all the better.

I agree with Frosty that contact with the local rock club would be useful.

"By hammer and hand all arts do stand."

[fishfinder401]

this particular piece while not very fine doesn't seem to be too coarse, but ill get a better idea of it once i get it to a flat surface, worst case scenario though i have a stone to flatten other stones with haha

I just sent them an email so I'm curious what they will say.

[ThomasPowers]

What we would say is "Ask the State Geologic Bureau---it's the next building over!"   (Currently working in a University Geology Department.)

[Frosty]

How about this for a crazy thought. Were I wanting to make a sharpening stone I wouldn't look at one USGS map of the area. I'd buy the grit I thought would serve and cast one using epoxy resin. If that didn't work I'd try Portland cement matrix with a little hardware cloth imbedded about 1/2" from the face. Say, 80-90% grit to 20-10& cement. 

The rock shop should carry suitable grits if not shop online. We're just sharpening knives not polishing them so 100grt. would be where I started. 

Of course that's just me, If I'm going rock hunting I'm looking for: semi precious stones, crystals, fossils, etc. Deb and I found some agates on the beach last summer. Next time we're RVing I'm taking my Roadside Geology, might find something cool. 

Boy, that last sentence triggered a memory, about 40 miles up the Glenn Hwy there is a large talus slope comprised of lenticular chert. I collected some a few years ago to see if it was worth knapping. I'm thinking a person could find some that's flat and smooth enough to sharpen blades. 

Frosty The Lucky.

[ThomasPowers]

IIRC "Practical Blacksmithing" had a bit on making your own emery wheels using grit and shellac.

[George N. M.]

But you wouldn't want to use a shellac and grit stone as a "wet" stone since shellac is soluble in water.  It would be embarrassing to dissolve your stone while using it.

"By hammer and hand all arts do stand." 

 

Wrong!  Shellac is NOT soluble in water, it is soluble in alcohol. 

[fishfinder401]

making them does seem interesting.... and maybe i will try that too, although while maybe not as practice, finding a natural one in my area just sounds... satisfying haha. 

as far as making on though... that does make me wonder about making a large artificial stone for an old style grinding wheel.... oh great now i have another project to think about haha!

[Frosty]

Oh I don't know George, if you used the right density of grit and amount of water, you could have a self sharpening wheel.

Making your own ceramic or thrown pottery clay, grinding or sharpening wheel has been done for I don't know how long, centuries probably.  Drying thoroughly without it shrink checking would be the trick, the rest just needs a BIG fire.

Frosty The Lucky.

[fishfinder401]

What if for the large grinding wheel you used a ton of abrasive grit and jaut enough epoxy to held it together?

[George N. M.]

No, George, wrong, wrong, wrong!  Shellac is NOT soluble in water, it is soluble in alcohol.  Another sufferer of CRS (Can't Remember S***).  Thanks to Slag for the PM memory jog.

"By hammer and hand all arts do stand."

[ThomasPowers]

(Well shellac does get white rings in the finish when you set wet glasses on top of it, used to be suggested that you polish them out with cigarette ash...)

Anyone have a link to that old German? film on cutting natural mill stones out by hand in a quarry?

I'd suggest reading up on some of the DIY books from the late 1800's/early 1900's for suggestions.   I'll check out that Scientific American Cyclopedia of Formulas I have.

One thing I will mention is that modern abrasives are generally *GREATLY* superior to earlier ones: stronger and more aggressive and more easily used---look up the old knife grinders in Sheffield who lay on a board above 8'+ diameter wheels to grind blades as that was the way they could get SFM on slowly spun by water power grindstones!   The treadle grindstones you see were designed for putting an edge on things not to shape them from the rough forging.