Hi, I'm a new forum member and a newbie when it comes to minerals, so I'll apologize in advance if I don't provide sufficient information or use incorrect terminology. I found this stone in my yard in Portola Valley, CA. I'm pretty sure it did not end up there naturally since I've never seen any rocks like this in the San Francisco Bay Area. It stood out to me which is why I grabbed it.
The rock is about 7" long
It appears to be a dark, grayish green in color
If you look closely it appears somewhat composite kind of like a granite
It has a "gemmy" quality to it in th