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
ARIA Award for Best Rock Album ARIA Award for Best Rock Album The ARIA Music Award for Best Rock Album, is an award presented at the annual ARIA Music Awards, which recognises "the many achievements of Aussie artists across all music genres", since 1987. It is handed out by the Australian Recording Industry Association (ARIA), an organisation whose aim is "to advance the interests of the Australian record industry." To be eligible, the recording must be an album in the contemporary rock, modern rock and active rock formats, and cannot be entered in other genre categories. The accolade is voted for by the ARIA Judging Academy,