please help identify

Hey! New here and hoping I could get some help with identifying this…. Geographic info: North Georgia and rock was found in a small creek that has underground river that has waterfall into the creeks and on other side underground river that flows under a tree and it’s roots and then out to the small creek and the creek is in the middle/bottom of to hills


Hi Stephanie,

A bit of a tough one. It’s a little hard to know if the rock is weathered - or we are looking at a weathered skin. I am assuming it is weathered.

I think I can see some quite large grains of a cream/beige mineral - maybe feldspar. There also appears to be some smaller grains of quartz throughout and maybe the smaller shiny grains (like on the large cream grain at the left) might be mica - maybe muscovite. Based on that I would guess a plutonic (intrusive) igneous rock but I am not confident of that. Possibilities could be granite, quartz monzonite, granodiorite or something similar. The large feldspar grains would mean that it would be porphyritic.

Cutting it with a diamond saw (maybe at a lapidary club) and some photographs of the slab with a ruler might help show the textures and help identification. Also identifying where you are on a geological map should narrow down the possibilities.

Looks like the same stuff Stone Mountain is made of. Like half the rocks in my backyard in Decatur GA