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
Latin Grammy Award for Best Portuguese Language Rock or Alternative Album Latin Grammy Award for Best Portuguese Language Rock or Alternative Album The Latin Grammy Award for Best Portuguese Language Rock or Alternative Album is an honor presented annually at the Latin Grammy Awards, a ceremony that recognizes excellence and creates a wider awareness of cultural diversity and contributions of Latin recording artists in the United States and internationally. According to the category description guide for the 13th Latin Grammy Awards, the award is for vocal or instrumental Portuguese Language Rock albums containing at least 51% playing time of newly recorded material. For Solo artists, duos or groups. From 2000 to