The Morgan Silver Dollar was designed by George T Morgan, was made from 1878 to 1921, and is one of the most popular US coins with collectors.
Most collectors and investors consider the 1884-O Morgan dollar to be a dog in every way: appearance, strike, and as an investment. There is no doubt that it is one of the most common coins in the series, regardless of grade. Almost ten million pieces were made and many of these escaped the destruction of the various government and private melting operations. Dealers estimate that at least 15% of the total pieces seen bearing the 1884-O mark are in mint condition. The majority of the pieces seen today, both circulated and uncirculated, have very poor strikes. Thousands of Mint State coins exist with very little high point detail on the obverse and the reverse. However, enough good strikes can be found to create a large MS-65 population bearing this date. In fact, the coin is also common in MS-65, though hoarders and investors are grabbing off as many of these as possible. Surface abrasions on the 1884-O coin tend to be minimal. (This seems to highlight the poor strikes even more.) The luster is unusually good. It is ironic, and very disappointing to find coins with a fantastic gleam, almost no abrasions, and a very weak strike. This is a common occurrence. Two minor varieties exist with regard to the mintmark. Part of the issue received an oval O and the remainder received a round O mintmark. Finding prooflike examples of the 1884-O Morgan dollar is an easy matter. A few of these are cameos and can fetch nice premiums. Most prooflike coins, however, exhibit little or no contrast between the fields and the devices. (Information contained above is from James B. Osbon's "Silver Dollar Encyclopedia 2nd Edition")