Birch Mountains kimberlite field shales interbedded with kimberlite at some of the diatremes are consistent with a Late Cretaceous age (Late Albian to Maastrichtian). The volcanic rocks of the BM field consist primarily of crater-facies pyroclastic kimberlite and resedimented kimberlite. They include massive layers, as well as bedded and graded layers of coarse lapilli alternating with layers of finer tuff. Lapilli and olivine phenocrysts are set in a grey-green matrix of serpentine, carbonate minerals (calcite, dolomite and magnesite) and clay minerals. Phlogopite, oxide minerals (ilmenite, perovskite and spinel), apatite and pyrite are also present. Diamonds and microdiamonds have been recovered from samples taken from
Kimberlite tailings at higher temperature to obtain Zeolite-A. The product is useful as builder in detergent formulation. With a view to assessing the potential use of kimberlite tailings in road works, the Central Road Research Institute engaged in a detailed laboratory study. Kimberlite tailings were characterized to determine their physical engineering properties. Results indicate that kimberlite tailings are a marginal material and possess adequate strength for use in the construction of rural roads. The feasibility of utilizing this material for the construction of various layers of road pavement by adopting stabilization techniques was investigated. A study was also undertaken to assess the