the black part is jet black and rock hard, nothing comes off after scraping on white paper, the pattern feels bit too hard also to be aspestos i was thinking maybe it was radiating pyrite
Not pyrite or asbestos from what I can see. As st denis suggests better pictures in natural light may help. As to hardness see if quartz will scratch it, paper really doesn't tell us anything but if you try a scratch test on a piece of white tile that may help.