Black stone

[HADJ]

PLS help know this stone

 

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[stdenis_jd]

Looks like biotite rich schist, but it's a bad photo. If you can take a picture of it dry and in natural light that would be more helpful. Being wet and the flash from your camera makes it very difficult to see what's going on with it

 

[HADJ]

this is another one

 

[HADJ]

I just one more clear

 

[old digger]

Welcome to tnet!

I would help if you gave us a locality from which it was found? Your item in the last photo looks quite similar to volcanic rock.

 

[stdenis_jd]

thanks for the new pics, but they aren't very helpful. The camera focused on your hands/fingers and not on the stone. If you can take pics that show as much detail in the stone as there are on your hands (I see good defined fingerprints lol ) it will help narrow it down.

Also, can you scratch glass with it? Looks like it might be silicon carbide (man made) but not sure yet

 

[HADJ]

I take new pictures .
The stone is very hard and scratch a granite but can not be scratched .
I found in volcanic place all the stone are granite and marble only .

 

[HADJ]

Me also first time I think is carbide .but I am confused.

 

[stdenis_jd]

Actually picture #2 on the last pics you uploaded, the one near the top seems to have the crystal structure of corundum. I'll bet these are a corundum complex of some sort. Black corundum is of course non gem-grade and is nicknamed Emery. If you have a junk piece of pure quartz, or even better topaz, see if you can scratch the quartz or topaz with your rocks. Corundum is much harder than either or them so that should give you your answer or just open up a new question lol

There is a glassy looking one there though, and that doesn't seem to match the others. Looks like mahogany obsidian. Does that one scratch or get scratched by granite? Problem with using granite is that it is a rock, not a mineral, so when you use granite you don't know if you're using the feldspars (6) or quartz (7) to test the hardness. You can also use a steel file which is a solid 6.5

 

[stdenis_jd]

Me also first time I think is carbide .but I am confused.

the new pics are very good, we can certainly exclude silicon carbide now

 

[HADJ]

Dear sir .
Thank you for your answer .
I just try to scratch the quartz with this stone but can not .in the picture you can see some black line from the stone means the stone who was scratch not the quartz .

 

[stdenis_jd]

yeah, it's definitely not corundum, so we have the hardness narrowed down between 6 and 7. I'll go ahead and say it's a type of schist. The black spots could be garnets, the shiny areas could be mica, without a close-up I can't confirm but that seems to be the most logical answer. As far as what type of schist I cannot say. Good job on the testing

 

[HADJ]

HI .
I make ne search in internet is black mica schist.