Buffalo Head Hills kimberlite field They have a low carbonate content, low abundances of late-stage minerals such as phlogopite and ilmenite, and a high abundance of fresh, coarse olivine. Based on examination of more than 700 examples, the BHH diamonds range in color from colorless to yellow and brown, and most are transparent and colorless. The majority are sharp-edged octahedra, but ~45% were dodecahedral due to resorption of octahedra. Inclusions of garnet, olivine, clinopyroxene and rutile were found in a few specimens. Buffalo Head Hills kimberlite field The Buffalo Head Hills kimberlite field is a group of kimberlitic volcanic pipes or diatremes in north-central Alberta,
Volcanic plug Volcanic plug A volcanic plug, also called a volcanic neck or lava neck, is a volcanic object created when magma hardens within a vent on an active volcano. When present, a plug can cause an extreme build-up of pressure if rising volatile-charged magma is trapped beneath it, and this can sometimes lead to an explosive eruption. Glacial erosion can lead to exposure of the plug on one side, while a long slope of material remains on the opposite side. Such landforms are called crag and tail. If a plug is preserved, erosion may remove the surrounding rock while the erosion-resistant