As of my last knowledge update in January 2022, there is no widely recognized and documented 1870-S Seated Liberty Half Dime.
The Seated Liberty Half Dime series was produced from 1837 to 1873, and the San Francisco Mint (S mintmark) did not officially begin minting coins until 1854.
If there were to be a claim of a unique 1870-S Seated Liberty Half Dime, it would be crucial to authenticate and verify its provenance.
Numismatic experts, grading services, and reputable dealers play a pivotal role in assessing the authenticity and rarity of such coins.
Numismatics is a dynamic field, and discoveries of previously unknown coins can occur. If you believe you have a unique or unknown coin, it is recommended to consult with experts, possibly reaching out to reputable numismatic organizations or institutions for further examination.
For the latest and most accurate information regarding specific coins or discoveries, especially those claimed to be unique, it's advised to check with reputable numismatic sources, auction houses, or relevant institutions specializing in coin authentication and historical documentation.
The Seated Liberty Half Dime series is a captivating collection within American numismatics, known for its intricate designs and historical significance.