One of just 35 to 45 pieces known, the coin was part of the estate of Hellen and Charles Mapes, of Reno, Nev.
Charles Mapes was a hotel and casino pioneer.
Paul Song, director of the Rare Coins and Bank Notes Department, said: “We are delighted with the result of the auction. Rare U.S. gold coins continued to bring exceptional prices.”
The 1870-CC $20 had been in the Mapes Collection since it was purchased in 1961 in a Kreisberg-Schulman auction of Feb. 16-18 at the Waldorf-Astoria Hotel in New York City.
Song explained that it can be considered a discovery piece due to the length of time since its last auction offering.
There are no Mint State examples of the 1870-CC extant and most known examples are graded VF to EF.
Song said the coin was a bit of a discovery to the consignor as he did not realize the coin had the famous and valuable “CC” mintmark on its reverse.
A Philadelphia coin from 1870 is worth around $2,000.
Bringing $142,875 was a five-piece 1915-S Panama-Pacific commemorative coin set. The coins were offered with the original case of issue inscribed PANAMA-PACIFIC INTERNATIONAL EXPOSITION COMMEMORATIVE COINS 1915 SAN FRANCISCO, U.S.A.
Song also reported that other gold coins in the auction brought strong prices.
A 1796 $10 graded AU-50 by Numismatic Guaranty Corp. realized $54,990.
An MCMVII (1907) high relief wire rim Saint-Gaudens gold $20 sold for $46,800 and a second example sold for $25,740.
An 1851 Augustus Humbert octagonal $50 gold piece, 880 THOUS brought $22,230, while an 1871-CC $20 fetched $21,060.
For more information about this and a Dec. 16 auction, visit the firm’s website at www.bonhams.com/uscoins.