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
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,