Birch Mountains kimberlite field Birch Mountains kimberlite field The Birch Mountains kimberlite field is a cluster of kimberlitic volcanic pipes or diatremes in north-central Alberta, Canada that were emplaced during a period of kimberlitic volcanism in the Late Cretaceous epoch. As of 2011, 8 diatremes had been discovered in the field, and diamonds and microdiamononds had been recovered during sampling programs. The Birch Mountain (BM) kimberlite field was discovered in 1998 and lies about north of Edmonton and northwest of Fort McMurray. It is part of the Northern Alberta kimberlite province, along with the Buffalo Head Hills kimberlite field and the Mountain Lake cluster.
Volcanic rock that after the mineral had crystallized it was partly again dissolved or corroded at some period before the matrix solidified. Corroded phenocrysts of biotite and hornblende are very common in some lavas; they are surrounded by black rims of magnetite mixed with pale green augite. The hornblende or biotite substance has proved unstable at a certain stage of consolidation, and has been replaced by a paramorph of augite and magnetite, which may partially or completely substitute for the original crystal but still retains its characteristic outlines. Volcanic rock Volcanic rock (often shortened to volcanics in scientific contexts) is a rock