In 2005, PCGS determined that all 1896-O, 1900-O and 1902-O Silver Dollars with so-called "Micro o" mintmarks were counterfeit. This announcement was based on the discovery that all three dates shared common die markers.
Q. David Bowers:
The following narrative, with minor editing, is from my "Silver Dollars & Trade Dollars of the United States: A Complete Encyclopedia" (Wolfeboro, NH: Bowers and Merena Galleries, Inc., 1993)
Unneeded dollars: Like many other dollars of the era, 1900-O dollars were not needed when they were minted, and many were relegated to long-term storage.
Hoard coins: After the New Orleans Mint was closed, many bags of 1900-O dollars were shipped to the Treasury Building in Washington, D.C. and in 1929 to the Philadelphia Mint for storage. Bags of 1900-O dollars dribbled out from the Treasury Building holding by the early 1930s, continuing through at least the early 1950s.
Unlike the 1898-O, 1903-O, and 1904-O, all of which were deemed to be great rarities in Uncirculated grade, the 1889-O, 1890-O, 1894-O, 1896-O, 1897-O, 1899-O, 1900-O, and 1901-O were on the market in bag and roll quantities in the early part of the 1950s decade. For example, Philip Maul, a Hudson, New York dealer, advertised rolls of these particular issues in The Numismatist in September 1953. In April 1954, W.E. Johnson of Santa Barbara, California, advertised rolls of 1900-O dollars for sale in the same publication. In January 1957, Postal Products Co., of San Francisco, had these rolls of O-Mint dollars for sale: 1881-O, 1882-O, 1883-O, 1884-0, 1885-O, and 1900-O. In the September 1957 issue of The Numismatist, Harry J. Forman advertised that he had Uncirculated specimens of the following New Orleans issues available in quantity: 1879-O, 1881-O, 1882-O, 1883-O, 1884-O, 1885-O, 1887-O, 1888-O, and 1901-O.
In October 1962, the 1900-O was front row center in the great dispersal of New Orleans dollars from long-term storage at the Philadelphia Mint. Hundreds of thousands were released. Wayne Miller wrote in 1982 that in roll quantities, 1900-O was believed to be scarcer than 1898-O, 1899-O, 1902-O, and 1904-O, and ran a close contest with 1901-O. Even so, today in the early 1990s there are plenty to go around.
Circulated grades: Worn 1900-O dollars are readily available, even though many perished in the private silver melts of the late 1970s. Demand is low due to the common nature of low-grade Mint State pieces.
Mint State grades: Most of the 1962-1964 release 1900-O dollars are in lower Mint State grades from MS-60 to 62, in which category an estimated 250,000 to 500,000 coins exist. In MS-63, 120,000 to 220,000 survive, and in MS-64 some 100,000 to 200,000 are believed to be extant. Even at the MS-65 or better level the 1900-O has no pretense of scarcity; 20,000 to 40,000 are around.
Striking varies, and specimens are encountered from weakly defined to sharp. However, most have the center of the reverse weakly defined, even if the center of the obverse is sharp. Others have a sort of wire-brush effect to the fields, radiating outward toward the rim, possibly the result of over-long die use. Cherrypicking will yield a well-struck coin with nice lustre, but some looking will be required.
Prooflike coins: In PL finish the 1900-O is readily available. Several thousand remain. DMPL coins are, perhaps, six or seven times scarcer. When seen, PL and DMPL coins are likely to show little contrast between the devices and the fields, and are apt to have distracting die-finish lines. Use caution when buying these. About a third of extant DMPLs are MS-65 or finer.
OLD REVERSE HUB: NARROW WING/NECK SPACE, SMALL STARS
VAM C-3 REVERSE
1. Medium Round O. Open 9. Breen-5670, many VAM varieties, including some with partially repunched date. Common Uncirculated from Treasury bags 1962-1964.
2. Closed 9. Breen-5672, many VAM varieties, including some with repunched mintmark and/or partly repunched date. Common from the Treasury release.
Dies prepared: Obverse: Unknown; Reverse: Unknown.
Circulation strike mintage: 12,590,000; Delivery figures by month: January: 1,550,000; February: 1,500,000; March: 2,000,000; April: 1,500,000; May: 1,500,000; June: 1,000,000; July: 630,000; August: 400,000; September: 1,000,000; October: none; November: 1,140,000; December: 370,000.
Estimated quantity melted: Millions under the Pittman Act; millions more in later private melts.
Availability of prooflike coins: Prooflike coins are readily available; DMPL coins are six or seven times scarcer. Most have negligible aesthetic appeal.
Characteristics of striking: Striking varies, but the typical coin is apt to be weak on the reverse.
Known hoards of Mint State coins: Many bags were released by the Treasury in the 1950s and in 1962-64.
The 1900-O is very plentiful in Mint State, but most pieces are in the MS-60 to 62 range.
Distribution of Dollars
The Annual Report of the Director of the Mint, 1900, told of distribution of dollars during the fiscal year: New Orleans: In mint July 1, 1899, 11,409,000; coinage, fiscal year 1900, 14,140,000; total, 25,549,000; in mint July 1, 1900, 21,197,000; total, 21,197,000; distributed from mint, 4,352,000.
1900-O (regular and O/CC) is the only 1900-1904 issue not known to have been struck with the new C-4 reverse. If specimens exist they are extremely rare!