The 1905-O Micro O Barber Dime was created when a die sinker used a mintmark punch intended for a quarter dollar which, ironically, is smaller than that used on the dimes. According to Walter Breen, this variety was discovered by Howard Newcomb circa 1912; yes, that's the same Newcomb who is famous for his reference work on die varieties of 1816-1857 large cents.
This is a relatively scarce variety made all the more popular because it is the only major variety of the series. The finest example is a single PCGS MS66.
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