Boskett, a part-time coin dealer, paid $450 for a dime purportedly minted in 1916 at Denver and two additional coins of relatively small value. After carefully examining the dime, Beachcomber Coins, a retail coin dealer, bought the coin from Boskett for $500. Beachcomber then received an offer from a third party to purchase the dime for $700, subject to certification of its genuineness from the American Numismatic Society. That organization labeled the coin a counterfeit. Can Beachcomber rescind the contract with Boskett on the ground of mistake?