Employee is an Equip Opr./Quarry Truck Driver. EE was operating a Quarry Truck, EE was waiting for EE's truck to be loaded when a rock ""spilled"" or ""fell"" from the Bucket of the WA-900 Komatsu Mach which was loading EE's truck, broke the driver's side window, hit EE on the L/thigh and fell to the floor of the truck EE was operating.