The 1878-S $10 gold piece is a moderately scarce date in circulated grades and an extreme condition-rarity in Mint State. Were this any other series, the mintage of 26,100 would be monstrously low, but this is a denomination and a type that was produced in very low mintages in many years, hence the 1878-S is priced as a type coin in low grades. The PCGS CoinFacts Condition Census for this date includes a cluster of AU58's, one (maybe two) low-end Mint State examples, and a single PCGS MS64. This date comes well-struck, often with good luster, but invariably with a bit too much wear and too many scuff marks and abrasions.
Heritage 7/2004:13996, $30,415
Stack's/Bowers 8/2016:3470, not sold
David Hall Collection - Bob R. Simpson Collection