Diamonds have inspired dreams of wealth and power throughout history. Until modem times, most diamonds were insignias of royalty and were beyond the reach of the com• mon person, who could only elicit visions of the astounding beauty and wealth brought forth by diamonds. It's no wonder that other gems and precious metals have historically taken a back seat to diamonds.
Some diamonds are so valuable that a person can literally carry a king's ransom in a pocket. A similar value in gold would mean one would have to have access to a forklift, as some of the most valuable diamonds in the world have been appraised for many thou• sands of times that of a similar weight in gold! It is no wonder that so many companies, geologists, and prospectors have invested time and money to locate and develop new diamond resources around the world.
Diamond deposits are not easily found. Diamonds occur in some of the rarest rock types on the surface of the earth, and when found, they are disseminated in trace amounts even in the richest deposits. The principal host rock, kimberlite, forms very small deposits. Being a relatively soft rock, kimberlite commonly erodes faster than the surrounding country rock and often is covered by thin layers of soil and regolith derived from adjacent rock outcrops. As a result, many kimberlites go unrecognized for decades. Thus it is necessary for the geologist and prospector to search for clues for the where• abouts of these hidden or partially hidden rocks. The clues are not easily found and require detailed detective work.
Kimberlite intrusives are generally exposed over relatively small surface areas. They occur in the form of pipes, dikes, and sills that may crop out over an area of a few hect• ares at the most. Other diamondiferous host rocks exhibit similar characteristics. For example, lamproite, another host rock, may occur in the form of dikes, sills, and small volcanoes. But lamproites are even rarer than kimberlite. Then there are other deposits that have been termed unusual or unconventional. Some of these are extremely rich in diamonds, and some will probably become prominent sources of diamond in the future.
If you are lucky enough to find an outcrop of kimberlite or lamproite, this alone is considered to be a significant discovery, as these rock types represent two of the rarest found on the earth. But this does not mean that you will find diamonds. Reported statis• tics suggest that only about 10% of all kimberlites in the world contain diamond, and less than 1 % contain commercial amounts of diamond at grades less that 1 ppm (part per million) (Lampietti and Sutherland 1978). The chances of finding diamonds in lam• proite are even less than in kimberlite. Thus, the odds of finding a commercial diamond deposit are not great. But through diligent exploration, one can increase the odds of finding a king's ransom.

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