You should be able to add some gum turpentine, and then let it sit for a while to give the turps a chance to penetrate the wax. If it was just wax, you could try heating it up gently, but I am not sure whether that will cause the verdigris particles to fall out. You might have to heat it until it's liquid (in a water bath!!!) and then stir it until it's all a homogeneous mixture, and let it set while stirring.