Opal mining in Virgin Valley bentonite clays needs a sharp tool. By cutting off a hardened steel tine from a pitch fork and welding on or leaving a t-bar to hold it  by, you have a surgical tool for extracting opals whole. The curves of the fork helps pop out clods on natural weaknesses in the flows that you are digging thru. Otherwise a small pick is needed to chip at harder stuff or go faster. It is directly related to how many pieces your opal comes out in. Some go to pieces dried in the bank and the tines help you see or hear by hitting them in the dust, the smaller pieces.  I pad my T-handles with an old sock then wrap duck tape around it securely to not get blisters. It can still get you between the fingers where your point goes out. Remember to never hold a clod to poke it; you will put the point right thru your palm or leg, we sharpen them on a grinder as the do still get dull or snap off. You cant pry with them much.