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
Grammy Award for Best Rock Instrumental Performance to Paul McCartney and the band Wings for "Rockestra Theme". From 1986 to 1989, the category was known as Best Rock Instrumental Performance (Orchestra, Group or Soloist). According to the category description guide for the 52nd Grammy Awards, the award is presented to artists "for newly recorded rock, hard rock or metal instrumental performances". As of 2011, Jeff Beck holds the records for the most wins, with six. Sting has received three awards, twice as a member of The Police -- although he had no part in the band's "Behind My Camel", the 1982 award winner which he did not