Cornubianite
“Ultra-high temperature contact hornfels”
Cornubianite is an extremely high-grade contact metamorphic rock (hornfels) that formed at temperatures approaching partial melting. Named after Cornubia, the Latin name for Cornwall, it develops in the innermost zones of contact aureoles around hot granite intrusions.
cordierite, sillimanite (fibrolite), biotite, quartz, feldspar, spinel, corundum (rare)
Cornwall (England — type locality), Dartmoor (England), Bushveld Complex margins (South Africa), contact aureoles worldwide
6-7
Cornubianite represents the absolute edge of metamorphism — just a few degrees hotter and the rock would have begun to melt into magma, transitioning from a solid rock into a partially molten migmatite.
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