I found this rock while hiking in Maine. It was sitting aIong the rocky shore line along the Gulf of Maine. There seems to be bits of black with green, along with a slightly transparent body and other little features. It's very beautiful and sitting in my collection. I use my hand to show scale below.
Well it is quartzose and feldspathic, but without seeing close-up (and really under a microscope), we can't see the petrographic textures, so we can't tell if it is igneous, hydrothermal or metamorphic (the macro- appearance leads me to think it is not sedimentary).
If it was more uniformly quartzose, I would guess it was quartzite (metamorphic).
But the large opaque white areas (feldspar) suggest it is pegmatite.
(Methinks I've given you some terms to go Googling!)