This limited circulation US coin is a first year Susan B. Anthony Dollar. This version of the 1 Dollar coin circulated from 1979-1981. It represented the second post WW-II example of a US 1 Dollar coin. It was preceded by the Eisenhower Dollar (1971-1978) and spiritually replaced by the similarly short-lived Sacagawea Dollar (2000-2001, 2009-2011).
The coin is a reeded-edged design made of nickel-clad copper core (75% Cu/25% Ni) and weighs 8.1 g. Its dimensions are 26.5 mm (1.04 in) wide and 2 mm (0.08) in thick. It shares similar dimensions and composition to the post-1965 Washington Quarter. This similarity to the Washington Quarter, caused unnecessary confusion and lead to the 1 Dollar coin becoming discontinued.
Observe
The observe features a portrait of social reformer Susan B. Anthony (1820-1906), who played a key role in women's suffrage. To the lower-right is the motto "In God We Trust". On 30 July 1956, the 84th US Congress passed a joint resolution, adopting it for official use. Since 1957 it has been a standard feature on all US currency.
At the lower-right of the portrait's neckline, is a "FG" mintmark. This mintmark represents the US Mint's chief engraver Frank Gasparro (1909-2001), who also designed the previous Eisenhower Dollar. An additional letter "D" mint mark can be seen at the upper-left of the neckline. This mint mark represents the US Mint (Denver).
Above the portrait is the text "Liberty", while below is the coin's "1979" mint date. These 2 elements are joined by 13 stars, representing the 13 colonies. They form an asymmetric wreath, with 7 stars on the left and 6 on the right.
Another notable feature is the 1 Dollar coin's strange inner rim. Which forms a hendecagon (11-sided) shape, a unique feature not seen in other US issued coins.
Reverse
The reverse features the Apollo 11 Mission Insignia, a feature taken from the Eisenhower Dollar. The insignia features a flying Bald Eagle, carrying an olive branch on the moon's surface. Earth can be seen in the background, above the eagle's head. The olive branch represents NASA's peaceful intent for Lunar Exploration.
Above the eagle is the Latin motto "E pluribus unum". This phrase is often translated as "Out of many, one". A metaphor for the federal system of the US government. A semi-circular can be seen begining above the motto and ending at the moon's surface.
The reverse header lists the coin's issuing nation, "United States of America". While the footer lists it's "One Dollar" value. Just as the observe, the reverse also features a 11-sided inner rim.
Additional Notes
The Susan B. Anthony Dollar was produced by all 3 US Mints: Philadelphia (P), Denver (D), and San Francisco (S).
The Susan B. Anthony Dollar was the first US coin to feature a "P" mint mark, since the WWII era Jefferson Nickel, all previous Philadelphia mint coins lacked a mint mark.
The Susan B. Anthony Dollar was unfortunately very unpopular with the general public, leading to the denomination to become discontinued.
Numismatists criticized the pairing of Susan B. Anthony's portrait, with the unrelated Apollo 11 Mission Insignia, as a poor and hasty design decision.
Due to their similar size to Washington Quarters, some businesses refused to accept Susan B. Anthony Dollars as payment.
Similar to the Buffalo Nickel, the Susan B. Anthony Dollar was opposed by the vending machine industry, due to its smaller size than the Eisenhower Dollar.
The Susan B. Anthony Dollar's 11-sided inner rim, was a suggestion made by vending machine lobbyist, to help calibrate machine to accept them.
The Susan B. Anthony Dollar was briefly reintroduced in 1999, as a temporary stop-gap measure, due to high demand for Sacagawea Dollar.