The Exchequer Gold and Silver Mining Company was among the turn-of-the-century firms operating in the Comstock Mining District of Storey County, Nevada. The first scan shows an early 1900s certificate for 100 company shares, at five dollars each. It's a simple, unissued specimen featuring a small vignette of miners loosening rock. As an investment vehicle, the certificate has been a steady gainer. Seven years ago, it would have cost you $5. Today, you'll have to pay $50. That's a 900% jump.

The Cobalt Central Mines Company was incorporated in Maine, as a holding company for firms doing business in the Cobalt mining district of Canada. Capital stock of $5 million was floated on the curb market. The elegant olive-green certificate illustrated was issued in February of 1911 and features a finely engraved representation of underground drilling activities. This piece has also been a solid seven-year gainer, moving from $10 to $100. That's another 900% improvement.

The third scan shows a dark blue certificate for 1000 shares of the Arkansas and Arizona Copper Company. The firm mined properties in the northernmost sector of the Verde Mining District of Yavapai County, Arizona. The certificate was issued in November of 1916 and indicates total authorized capital stock of $6.75 million. The piece was printed by the American Bank Note Company, a historically important engraver of currencies, postage stamps and stock/bond certificates. This specimen is up 500% ($10 to $60) in seven years.

The next sample is a 1927 certificate for five shares of the Magma Copper Company. Organized in 1910, the firm was noted for low-cost copper production at facilities in south-central Arizona. It became one of the largest copper producers in the United States, before being acquired in the mid-1990s by Australia's Broken Hill Proprietary Company. The certificate features an impressive vignette of one of the old mining operations and has an ornate blue border. The seven-year gain for the piece is an impressive 1150% ($4 to $50).

Next is a businesslike, but attractive certificate for 100 shares in uranium miner United Western Minerals Company. The paper was issued to Francis I. Du Pont & Company in August of 1957 and sold to Brown Brothers Harriman six months later. Bankers Trust of New York served as registrar. Chase Manhattan Bank was the transfer agent. Certificate printer GOES provided the firm with a bright green version one of its classic designs. It's another popular specimen, having run from $4 to $40 (900%) since 2002.

The final scan shows a handsome 1958 certificate for 100 shares of the Phelps Dodge Corporation. The company was founded in 1834 by import-export traders Anson Phelps and William Dodge. With westward expansion of the frontier, the firm turned to mining. At one time, it was also one of the largest U.S. producers of lumber. Phelps Dodge was acquired by Freeport-McMoRan, in 2007. The certificate features an allegorical Grecian figure and a wonderfully detailed depiction of an open pit mining operation. Seven years ago, a canceled sample would have cost you $5. Now, it's a $40 item (+700%).

While not all twentieth century mining certificates have done so well as these, seven-year gains have routinely been in the 200%-500% range and long-term owners are undoubtedly well pleased. Still, the goal of investment is maximum gain and investment-oriented collectors tend to concentrate on pieces with certain important characteristics. Condition counts, of course. The Exchequer certificate pictured above is over 100 years old, but it looks like it was printed yesterday. The Phelps Dodge and Magma specimens have good potential, by virtue of high company name recognition. The Arkansas and Arizona Copper sample was produced by a famous engraver and the United Western Minerals piece represents a popular collection niche (uranium). The Cobalt Central Mines document looks nice and that alone would be enough to attract interest, but the firm was once beset by accusations of fraudulent misappropriations and a whiff of old scandal does a certificate no harm.

Larry Schutts has invested in high grade collectibles for over twenty years and recently opened an online Collectible Investment Store.