According to the pilot, he was departing the heliport at the oil rig platform and had brought the helicopter into a low hover. While in the hover, the tail rotor struck a two foot vertical lightning rod attached to the platform edge causing damage to the tail rotor blades, horizontal stabilizer, wrinkling the tail boom, and displacing the tail rotor gear box. The pilot reported no mechanical anomalies with the helicopter prior to impact. The pilot stated that he had observed the lightning rod placement during previous landings on the platform, as well during the current operation.