Ultramafic rock but there are ultrapotassic and highly silica-under-saturated rocks with >18% MgO which can be considered "ultramafic". Ultrapotassic, ultramafic igneous rocks such as lamprophyre, lamproite and kimberlite are known to have reached the surface of the Earth. Although no modern eruptions have been observed, analogues are preserved. Most of these rocks occur as dikes, diatremes, lopoliths or laccoliths, and very rarely, intrusions. Most kimberlite and lamproite occurrences occur as volcanic and subvolcanic diatremes and maars; lavas are virtually unknown. Vents of Proterozoic lamproite (Argyle diamond mine), and Cenozoic lamproite (Gaussberg, Antarctica) are known, as are vents of Devonian lamprophyre (Scotland). Kimberlite
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