We all love to see that first glimmer of gold when it peeks out from under the black sand in our pan, or feel the weight of a nugget in our scoop when we dig a good target. But sometimes things don’t go quite so smoothly.

First, in order to compensate for the diminishment of purchasing power that usually accompanies rising inflation, investors normally have demanded higher interest rates on their investment assets. This was particularly true in the 1977-81 era when inflation soared to almost 20% and interest rates rose to roughly the same level.

There are three basic power sources for rock drills—electricity, gasoline and compressed air. Before we go into big pneumatic drills, we’ll start with a quick rundown of each.