The flight instructor in the helicopter reported that he instructed the pilot receiving instruction to shoot an approach to a sandbar in a riverbed. The pilot approached to the south and the wind was about 20 to 25 knots from the south. About 20 ft above the ground, the instructor took the flight controls due to a steep and fast approach and initiated a go-around. He performed a climbing left turn to the north. The helicopter descended and he was unable to maneuver the helicopter into the wind. The helicopter landed hard, bounced, and yawed to the right. The helicopter contacted the ground again and rolled onto the left side. The main rotor blades struck the ground and the tailboom separated. The helicopter sustained substantial damage to the tailboom. The flight instructor reported that there were no preaccident mechanical failures or malfunctions with the helicopter that would have precluded normal operation.