[1] As of 2011, 8 diatremes had been discovered in the field, and diamonds and microdiamononds had been recovered during sampling programs.
Unconsolidated Quaternary sediments that reach thicknesses of more than 150 m (490 ft) now cover the bedrock in the area, so the diatremes were located primarily by aeromagnetic surveys followed by drilling.
[2] According to radiometric dating the BM diatremes were emplaced about 70 to 78 million years ago during the Campanian to Maastrichtian stages of the Late Cretaceous epoch.
Phlogopite, oxide minerals (ilmenite, perovskite and spinel), apatite and pyrite are also present.
Diamonds and microdiamonds have been recovered from samples taken from the Phoenix and Legend pipes.