Rock flour consists of clay sized particles of rock generated by glacial erosional actions. Some of these actions include:

• glacial migration , where the glacier grinds against the land surface and erodes it away
• freeze thaw , where the act of water freezing and expanding in cracks helps break up rock formations

It should be noted that these particles are not clay, but typically ground up quartz and feldspar. Rock flour is carried out from the system via meltwater streams, where the particles travel in suspension. Rock flour particles can travel great distances suspended in fluid. Dried rock flour can be carried by the wind great distances and deposited in thick layers, where it is called loess.

John D Hamaker was a man who studied the role trace mineral spectra distribution plays in health. He advocated conversion of all hardware in mimickers of this natural process (exposing a fresh rock dust supply to biospherical absorption / transformation) in order to take over and thus stave of one of the most clockworklike reasons climate changes (ice ages) happen regularly: trace depletion.

Another person noting lack and/or superabundance (toxicity) levels of traces (but instead of a focus on climate and ice age cycles he zeros in on BSE - mad cow disease) is Mark Purdey.