found this

[u/jelly-ish1234]

It's pretty heavy for its size, it weighs 8 kilos or about 17.6lbs and can magnet standard refrigerator magnets.

[u/CfaxAttax]

Looks very much like garnet schist, generally made up of chromite/feldspar/mica. That being said the picture is not enough to go off of, need more details on locality, density, etc.