Kimberlites are blue volcanic rocks which tend to be diamondiferous. The word kimberlite is derived from the name of the South African city “
Rough diamonds were created over the years 150-250 kilometers deep within the earth’s core. They reached surface level inside kimberlite or lamproite stones (the latter is the second kind of volcanic rock that tends to be diamondiferous) through volcanic eruptions that took place at hundreds of sites through small cracks in the earth’s crust.
Not all kimberlites contain rough diamonds, but the discovery of such rocks arouses anticipation because of the chance that a major deposit may have been found. The existence of kimberlites can be discovered using electromagnetic testing conducted from the air. However, this test does not determine if the kimberlite contains diamonds: To determine this, tests must be conducted on the gravel in order to search for mineral indicators, or minerals that point to the presence of diamonds in the kimberlite.