Wow, nice rock.
Seriously, it'* a chunk of granite. There are so many different varietes of granite it isn't ven funny. "Granite" is almost as general a term for bedrock as "dirt" is for soil.
Granite just refers to a stone composed of feldspar, quartzite, and a few other things. It doesn't mean any specific amount of anything. Looks like that chunk is pretty high in quartzite, low in feldspar, and has a goodly proportion of something with a high iron content. I'll try to show his to my Dad on Saturday. He and Mom both have their bachelors in geology(how they met), and Dad is ABD for his Masters, as well.