Minerals/Gemstones WHAT IS IT?

[Eqnn]

Hello I just found a box of a bunch minerals and stones and have no clue what most of them are! They could be real or pieces of colored plastic, I do not know. Here is one, I have MANY others.

Black/ dark grey. Really lightweight. This one looks like plastic but it could be something else??

 

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[stdenis_jd]

Pictures in natural light would be better, the color and structure is obscured by the dim lighting.

Almost looks like man-made silicon carbide, but I doubt it. Could be scoria? I'm just guessing until you can get better/closer pics

 

[Eqnn]

Here are some photos I just took outside in the natural light. Hopefully these are helpful, Thanks for your help so far.

 

[stdenis_jd]

can you see if it will scratch glass? Also is it lightweight for its size (considering it's very porous)?

 

[IAMZIM]

If it is plastic, depending on how dense it is it may float in water. Just a suggestion.

 

[Crabs]

Glassy Volcanic Pumice