Rock dust is a byproduct of the quarrying industry and results from rock crushing. In the industry it is known as blue metal, cracker or crusher dust.
Landscapers use rock dust for filling holes, bedding paving stones and mixing with cement. More recently its applications have broadened to other areas and its true importance is becoming apparent.
Over 100 years ago Julius Hensel wrote a book called Bread from Stones, which explained how crushed rock could improve soil fertility. His cause was taken up some nine decades later in the early 1980s by the late John Hamaker and Don Weaver. They asserted that impending climate change could be ameliorated by massive-scale soil remineralization combined with reforestation to provide a vegetative carbon dioxide sink. Their book, Survival of Civilization, was a landmark, while their warnings of climate instability have essentially come true.