From the images provided, my opinion is quartz or serpentine, with jade running a very distant third. As Smokey stated above, location found can rule some possibilities out. If quartz, the likelihood of staining is high. Scrubbing with any detergent will help determine that. Enjoy.
Now it looks like serpentine. Much like that found on beaches near Gold Beach and Brookings, Oregon. Green quartz is still possible, but the cleaned stone looks more to serpentine. Jade is still unlikely, in my opinion. Still, cutting quality serpentine (can not determine this by photo alone) is still a good find.
Time for more coffee.
Edit: Blew up the images and noticed the white stringers. That is quartz. The stringers are quite common in serpentine found in costal areas of southern Oregon and Northern California. I am now convinced you have serpentine. Cutting quality? A good lapidary with experience with this type of stone will tell you. It looks good, but images do not
tell all.