Sites with ore often exhibit a surface deposit of some sort. When the material being sought is chemically bound or when it is microscopic, it can make the process of prospecting more challenging. But if we look at the situation in California's gold country, for example, we see that most of the gold was in the form of low levels of gold dust that required a great deal of washing - and good pairs of eyes and tweezers - to recover. But the area was first identified as gold bearing because of the discovery of a nugget at Sutter's Mill in 1848 (resulting in the '49 Gold Rush).

Most often these sorts of surface deposits were what tipped off early prospectors. The Cornish, for example, first retrieved tin from streams, and were, in fact, called "streamers." As surface deposits were declined, miners began to chase ore bodies underground, a pattern followed in both Cornwall and California - but also elsewhere.