Black Glass-Like Stones in CT

[Brijaws]

While metal detecting in my backyard today (South-Western Connecticut), I can across these Black Glass Like stones (like to image below). They are not Metalic (per my metal detectors) and just happened to in my dig site buried about 12" under a layer of root and rocks. They have a very metalic like shine to them but they are deceiving light in weight (almost like a graphite). I did the typical google search and have read everything from it being Slag to Obsidian. Some of the tests I have done: 1) Scrapping on the sidewalk leaves no black line. 2) I cant seem to scratch it with a nail. 3) When squeezed with some channel lock plyers it does crack like you would expect from a piece of glass leaving a shinny surface and somewhat sharp edge. 4) I tried burning it with a Torch and it at first crackels and pops (maybe surface debris?) but than just glows red but does not appear to burn, melt or smoke.

https://photos.app.goo.gl/BNdb6CbiA4xTIs2B2

I don't know if Steel or Coal Slag is super lightweight or not or if it would burn or smoke when torched. I am also not sure if they are native to CT as I found them in proximity to another little honey-hole in which i found a bunch of 1900-1920 relaics that appeared to have once been in a wooden box (as I found metal box strap, hingers and other signs of things burried) thou they were not in the same location (about 20' away).

Any thoughts?

 

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[jeff of pa]

Welcome to TreasureNet ! I moved your post to Rocks.Gems.
More likely to get an answer Here.



The top one does look like Coal to me

 

[Brijaws]

Thanks Jeff. It might be the camera angle but they all have a very metallic reflective shine and crack like glass. I also tried scratching across a bunch of different surfaces and I cant get it to leave any marks behind. Its just odd

 

[jeff of pa]

obsidian and melted glass come to mind

 

[loco oro]

I believe that to be slag, take pliers and pinch a small edge it will crush and leave translucent glassy shards,or dust they will be sharp.look at the gas bubbles around edges on the top pic also

 

[IAMZIM]

Does it burn? I looks like either chunks of tar or it could be bituminous coal, either one should burn. The light weight of them makes me really lean toward hardened tar. Try a hardness test? If it has a hardness of 7-7.5 it could be Schorl.....

 

[Brijaws]

I believe that to be slag, take pliers and pinch a small edge it will crush and leave translucent glassy shards,or dust they will be sharp.look at the gas bubbles around edges on the top pic also

It does crush like glass but the shards are not translucent as far as I can tell. I also really dont see any Bubbles - when I snap a piece in half, the break and really clean and smooth inside.

 

[Brijaws]

It does not burn - or not like I would typically expect. I took a Propane Torch and held the flame on the stone for about 30 seconds. Its glowing red but it did not SMOKE or change shape at all and when i removed the flame it just cooled back off quickly. It is light. Picking it up you would think it was Plastic or Graphite.

 

[Eu_citzen]

Will a knife scratch it?

 

[Brijaws]

No, I tried scratching it with a nail but it doesn't mark or etch - but it is brittle

 

[Eu_citzen]

No idea. Slag seems reasonable, but it could also be a curious freak of nature of some sort.