Can I assume from your profile that you found this in Curry County? If so, I do have a few ideas. Taprock suggested it might be green quartzite. He could be right. Another possibility is serpentine, which in found in Coos, Curry, and Del Norte counties in a variety of whites, greys, and greens. While the texture appears more like quartzite, it could just be the image. There are other possibilities, such as jaspers, but again, the texture does not look right.
It would help if you can pin down where you found it.