What kind of mineral is this ?

[Salvatore]

Would someone know what kind of mineral or minerals that are in this rock. The darker surface layer is like glass or something created under tremendous heat and pressure to leave such a very hard outer surface.

 

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[DDancer]

Looks to be hydrothermal in origin Salvatore. At a guess the hard mineral might be akin to chalcedony with a very high iron content. The luster looks right as well as some of the formation. Difficult to say but handsome enough.

 

[Eu_citzen]

I'm also into the quartz-range as the host rock. As for the metallic looking mineral, I'm uncertain.
I'd go about doing a streak test & will a knife scratch the black stuff?

 

[Salvatore]

Did scratch test in the black areas and can not scratch surface. Holding piece on different angle in light shows metallic Look under the darker areas besides the areas that looks metallic already.

 

[Moesia]

Crack one part of it then post some images, try to keep them less blurry and in better lighting.