The thing is a picture is often not enough to ID a rock. It would help if we knew if the rock seemed light or heavy for it's size. Rub the rock on a piece of porcelain like the underside of a toilet tank cover if you can't find anything else. Look at the color left behind.
See if the rock is soft enough to where a penny will scratch it. If not go to a nail, then a piece of glass.
These tests will help classify a rock. It's the fun part.
It does appear to be Actinolite. Nephrite jade is closely related. Often the two are misidentified.
Kray Gelder is correct that Actinolite is a form of asbestos. It's generally considered to be more dangerous than other varieties of asbestos so I too would suggest leaving the rock intact.