Question for you rock hounds.

So today I went to the house of one of my surfing buddies. He had a.stack of rocks I was admiring And I joked about that tendency that is a side effect of HAD where you look at random rocks and say, "Hey, I'll bet I could hone a razor on that."... Then I saw this one and actually did say that.
Attachment 331200
Attachment 331201
To which he replied that I should take it. At first I thought it was slate because it looked very gray in the shade but in the bright sun and looking at the little chips off of it...
Attachment 331202
Attachment 331203
...you can see that it is very green and has a very even sparkly mineral to it. I asked him if he knew where it was from and, as he is a bit of a hoarder, he said, "That might be from Alaska... Or from North Carolina. One of the two."
Sooo... I'm wondering if anybody has ideas of what it might be. I'm thinking maybe basalt from what I could see from pictures on the internet. It's very dense and very heavy for its size. I thought that I would smooth off that top side and lap it down. It also seems very hard and if nothing else it might be a good slurry stone.

Any ideas?

Edit: Oh, and also if you thought it might be good for honing.

It's not slate. Though slate comes in many colors it's usually in layers that are obvious and is very fine grained which that it not. Basalt is dark, very dark almost black.

With any rock unless it's you have a fresh surface weathering can make the outside look totally different than the inside.

From what you are saying sparkly and little chips fall off that could be mica falling off. It could be granite or many other things.

Well no chips falling off. It looks like it was chipped from hitting something. I do know that slate comes in many colors...I guess I didn't say that right. It's not the color so much that makes me think it's not slate. It's that it doesn't seem like it's layered.
I'm going to take the diamond wheel to the top of it then lap it on SIC and see what I get. I just wanted to post some pictures before it was cut to see if anybody had an idea.

I'll venture a guess at a quartzite.
If it is, it may make a good hone but will take some work to lap it.

I thought that might be it also and BOY are you right about taking a lot of work to lap. I figured I would "just" knock down the high spots with the cutting wheel or the grinding disc on the angle grinder. Yeah, well the angle grinder barely even touched it. The belt sander with the Al oxide belt did a little better but that makes an unpleasant mess so back to hand lapping on the diamond plate first. I have one I got in a lot of stones that I don't really use for much as it is too course. After that it will be back to the SIC plate. What is so far revealed though is a beautiful medium dark green and almost gem like smooth surface but opaque. Think of a yellow coticule except green and shinier. I can't wait to see how it turns out.

Please, post pics of your progress with it.
My quartzite cut fast with slurry from a diamond plate on one side and give a nice frosty bevel with oil on a well prepped and burnished other side.
If you're happy with it after lapping, you may want to find someone to cut it so you can use 2 sides. Double the lapping fun:gl:

I had actually thought about cutting it in half or possibly into three. I think three would be a little bit too thin though. I think that would take more than just a wet tile saw as hard as this thing is. Probably need to take it to a granite cutter I would imagine.

If it's quartzite that's metamorphosed sandstone and is tough stuff indeed. You need a proper saw to cut that stuff like a diamond saw.

This is a pic of some purple quartzite found in the devils lake area of Wisconsin, unique stuff.

I have a friend who has a tile saw but I'm afraid that this stone is just a little big for it. The wet tile saw will cut it I'm sure but it is usually used for tile which is normally 3/16 to1/4 inch thick and certainly always less than an inch. Maybe I'm wrong but I'm sort of thinking it would be like trying to cut a railroad tie on the table saw. You could do it but it's really pushing the boundaries.

Quote:

---

Originally Posted by thebigspendur

This is a pic of some purple quartzite found in the devils lake area of Wisconsin, unique stuff.

---

Ooh pretty stuff.

You have a college nearby? Contact the Geology Dept. They usually have a lab and true lapidary saw they might let you use.

Quote:

---

Originally Posted by thebigspendur

You have a college nearby? Contact the Geology Dept. They usually have a lab and true lapidary saw they might let you use.

---

Yeah, That's a good idea. I was thinking about taking it over there anyway just so I can get a positive identification on it.

Once you get a big enough patch lapped flat you can do some testing to see if it's even worth going further. I've learned to pick up some small pieces of given layers for testing, (I know that you didn't have that option on this stone) The lapping time goes up exponentially with the area. SiC on a piece of granite is my preferred means of flattening. I try to start with naturally flat surfaces. High spots can be removed with a series of shallow saw cuts and then breaking or chiseling the leaves of stone between the cuts.

Good tips!
So, as requested here's some progress pictures.
Here is what the cutting wheel did after about 5 minutes or so.
Attachment 331226
Damn! I guess that's not going to work. So I switched to the grinding disc. Here's what it did after about 5 -10 minutes.Attachment 331227
Double damn! So I switch to the belt sander. It worked much better but, as stated, it was a big dusty mess in the garage which I didn't stick with for more than a couple of minutes because of it. So then I went back to the manual work and so far this is what I have gotten.
Attachment 331228
So you can't really see how shiny it is in this picture but you can see on the top left and bottom right corners that have lapped out the color which is that beautiful kind of forest green. It kind of reminds me of that British Leyland British Racing Green. It's going to be a lot of work for sure to get this to be usable but I have a real good feeling about how this stone is going to turn out as a small natural stone.

Hard to tell from the pictures, but I'm thinking schist. I tried a few pieces of schist and my results were not worth a ...., but I have heard of schist being used for hones so some of it must be OK.

Good luck :tu

I’ve cut a few rocks. I’ve also got some tile saws. Saying tile saw does not really define it. It looks really hard. You could try to split it. It looks volcanic. Which one it’s tough to say. I’ve made hones from volcanic rock. I’ve given up on that. Not that you can’t get good hones. They do take forever to lap. If there are granite counter shops around, you could ask them to cut it down. Then you still need to lap it. Under water works best. One of the very difficult things I have found in finding good rocks is having the matrix very consistent. Mostly I have been focusing on uniform slate and metamorphic rock, it is way easier to work with.

If you are going to be doing a lot of exploration for hones it might be convenient to get a vibrating lap machine. You just add water and some media like alumina or cerium oxide and let it run a few days and you have a nice mirror polish.

Attachment 331272

I see. That's a very intriguing proposition.

Edit: I saw one called Vibra Lap...that sounds like something you'd get at the nudey bar.:rofl2:

Well, the plates on the machines are interchangeable since once one is loaded with a certain grit or material you use another for a different material so I guess if you had a mind to you could fill one with some kinky material and have at it with your....censored....

You know about this thread right? https://sharprazorpalace.com/hones/1...ver-there.html

Yes I did but I couldn't find it. Thank you.