Ron Guth:
The 1879-CC Silver Dollar is a very popular date. As one of the scarcest CC-Mint Morgan Dollars, it has an allure all its own. The mintmark is found either rusted or unrusted. The rusted version is often called the "Capped Die" or the "Capped CC." Of the two varieties, the non-rusted version is the most common and has a certified population about twice that of the Capped CC.
Hundreds of MS63 and MS64 examples have been certified, but collector demand keeps prices high. None have been graded finer than MS66.