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 which consists of 1000 members from different areas of the music industry, and is given to a solo artist or group who is either from Australia or an Australian resident. The award for Best Rock Album has been won by Powderfinger the most time, with three wins, for: "Internationalist" (1999), "Odyssey Number Five" (2000) and "Vulture Street". In the following table, the winner is highlighted in a separate colour, and in boldface; the nominees are those that are not highlighted or in boldface. ARIA Award for Best Rock Album The ARIA Music Award for Best Rock Album, is an award