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My grandfather's find

I have no idea the orgian or when, but I found this in our yard with some others, my grandfather drove log truck and brought grandma rocks for garden. Not sure what it is but it’s really dark. Any help or ideas would be appreciated. Scale is broken so I’m not able to weigh at moment. Hardness is 7 , heavy by touch. Thanks

Slag glass? :thinking:

Could be Blue Ridge Mountain Quartz


If there is anything more I could do to help identification please let me know? I do have a few chunks of it

I think it could be flint.


Black agate?

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Interesting, I will take a look at others, thanks you kindly

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Thank you all for your opinions, I have some work to do and hopefully I can come up with one of these suggestions you all have said.

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Good Luck :nerd_face::purple_heart::pray::four_leaf_clover::four_leaf_clover::four_leaf_clover:

Another idea would be to take this to a local University geology department professor or to a local Gem and Mineral Society meeting. -royjohn


I agree with it being flint. I’m curious. @chrish70724 please keep us posted!

What county and state was this found in? Where did your grandfather drive? the geology should assist in narrowing down the id of this cool-looking rock.

This is a very interesting rock.
Could you please do a specific gravity test?
It will allow us to help you figure out what this could be. It will give us a small hint and hopefully narrow it down.

It does look like some kind of flint/chert. It would help to know what area of the country this was found in.

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Yes I will do a gravity test and post results, from what I remember my grandfather logged all over Idaho. I asked some family where abouts did he find certain rocks and the one response I got was everywhere between boise county and south to Elmore county Idaho. I apologize for not knowing exact location for he passed on years ago. I can do test requested and I will also photo other peaces of it for you all. Thanks for interest.

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Sorry it took so long, but here are my test results, I only have done this a few times so I might not be spot on .
453.5 g of water
425.5 g stone on bottom
170 g stone floating.
Stone was fully emerged, I’m still learning equations so forgive me for not being on point. Thanks for your time and hope this helps .

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Chris, It was suggested to get the SG, and you’ve done a good job at trying to determine the SG. However, you are looking at a rock that has mixed minerals. So the readings would be combinations. On top of that there appears to be voids and likely inner cavities. As such it would be even more fruitless to try to make a SG ID. If you are looking at identifying a specific area, then cut a piece off that is a clean representation and polish a flat surface. …and take the RI.

But quite honestly I think you will end up finding, as has been suggested 2 or 3 times in the comments; you have a type of quartz.

Here are a couple other pieces I have

And that I will do, thank u kindly and for all your info. I shall get back to you here soon.