Largest transaction for single numismatic item

The largest known transaction for a single numismatic item took place on 7 November 2001 when an 80 lb (30 kg) pioneer gold assay bar retrieved from the 1857 shipwreck SS Central America was bought by an anonymous buyer for $8 million (£5.5 million). The gold bar (dubbed the 'Eureka') measures approximately 2.5 x 4.5 x 10 in (6 x 11 x 25 cm), weighs 933.94 oz (29,048.78 g), has a 0.903 fineness and is stamped with a face value of $17,433.57 (£11,958) and serial number 1003. In 1857 gold was priced at $20.67 an ounce.After lying for 130 years at 8,000 ft (2,438 m) in the Atlantic Ocean, the Eureka ingot and more than 5,000 pioneer gold coins, US gold coins, smaller gold bars, nuggets and dust were recovered by a scientific team in the late 1980s. The side-wheel steamship SS Central America sank 160 miles (296 km) from Cape Hatteras on 12 September 1857 when it was headed for New York from Panama. Unable to weather a hurricane it sank after its boilers failed on 11 September with the loss of 426 passengers and crew out of a total of 578 persons on board.