Mother/seed coin. Northern Sung (960 - 1127 AD), Emperor T'ai Tsu (960 - 976 AD, First emperor of Northern Sung Dynasty), orthodox script 'Song Yuan Tong Bao' mother coin for iron coin. 3.4g, Bronze, 24.64mm. 'Song Yuan Tong Bao' is the first series coins of the dynasty. Note: This is NOT iron mould bronze coin/Tie Fan Tong (bronze trial cast model for coin inspection to ensure the quality before cast iron coins officially). Extra fine and very rare.