Rock ID please!

[Knotty]

Hey everyone!
Found this rock while digging in my backyard, anybody know what it may be?

I hit it with a hammer and it made a precise split through the rock.
Has a few porous spots and it's black in color.

Take a look!

[Knotty]

Anybody know anything about it? Tried looking online but can't find much..

[Sasquatch]

Can you get a better pic in the light. It's hard to see

[caveman2533]

looks like burned brick
does not look knappable in the least and the black looks to be oxidized cracks in the red bricks base material.

[Knotty]

Here's another picture!




I don't think it's a burnt brick, you may have thought about that because of the red (ish) layer on top of the rock, but that's because it has been under clay soil for who knows how much time! 👍

[JoJoDapyro]

It doesn't look good at all to me. Bottle bottoms, toilets, tile are all a quick fairly simple knappable material. Do a search on stone in your area, and then look at what type of fracture it has. You want stone that has a conchoidal fracture.

What you want will have a waxy luster most of the time.

[YosemiteBen]

looks like a chunk of basalt to me.

[Dakota Kid]

It has bubbles and reminds me of some of the slag glass or industrial coke I find along the lake sometimes. Slag glass can be a good material on rare occasions, but the bubbles put it into the not so good category.

[mullet]

I agree with Ben, lots of Basalt in your area.

[Knotty]

Great, thanks for the help everyone! 😊

[caveman2533]

are you anywhere near iron  or steel industries.

[Knotty]

Yes I actually am caveman2533 , there´s a huge Steel Industry named USIMINAS here. Why the question?

[Dakota Kid]

I would assume caveman shares my opinion that your rock is slag of some type. Slag is a byproduct of smelting steel or iron. It's what floats to the top after the iron ore becomes molten. Typically it's skimmed off and discarded into the nearest river. Depending on what impurities are present in the ore, slag can range from solid hunks of glass of any color to bubbly hunks of what looks like coal and everything in between. Often there are little balls of steel in the slag and the bubbles usually contain a sulfur gas and stinks like rotten eggs when you break it. You should do some investigating and ask around to see if anyone has found any slag glass. Occasionally you can find some high quality glass in fist sized chunks sometimes larger. That type of slag is comparable to obsidian and is excellent for knapping.

[caveman2533]

because it looks  not like slag but the furnace lining which is often made of a fire brick material and will fuse together when it is heated to melting temperatures that melt steel.  It will be laden with cracks that oxidize and will have thin layers of black oxidation on it, that is the interface surface where molten metal and liner surfaces meet. It looks like the furnace liner, and it is torn out and relined every so often. It is dumped by the truck load where ever they can get away with it. It  is furnace liner, not gonna be knappable.  The slag itself can be knappable, much more glass like.

[Knotty]

Awesome!  Thanks for the great explanation, always good to learn something new 😊