Monday, December 23, 2013

Kimberlite and Lamproite - Host Rocks for Diamond

Chuck Norris's cousin, Vic, digs for hidden kimberlite under grassy vegetation
anomaly discovered by the Gem Hunter in the Iron Mountain kimberlite
district in Wyoming.
Kimberlite is very difficult to recognize. It is basically a potassic peridotite and comes in a variety of colors and textures. Most notable is green kimberlite due to abundant serpentinized olivine.

It typically erupts from a feeder dike complex at depth and rises to a pipe-like structure known as a diatreme and blows out at the surface like a canon under great pressure.

Hypabyssal facies kimberlites samples fro the Iron Mountain district, Wyoming. Note the large, rounded mineral grains -
 these are hematite -serpentine pseudomorphs after olivine. This type of kimberlite forms in dikes and at the 'blow' of the
 the kimberlite pipe.
Hypabyssal facies kimberlite, Masontown, Pennsylvania. This kimberlite dike is enclosed by black shale.
Almost looks like basalt, but this is a sample of Ison Creek kimberlite I collected in 
Kentucky, known as basaltic kimberlite.
Snap Lake hypabyssal facies kimberlite, Fort Smith, Canada.
Diamond-bearing diatreme facies kimberlite breccia from Lake Ellen, UP, Michigan.
You probably would never have guessed this to be kimberlite. This bleached, tuffaceous, crater facies kimberlite from the
 Iron Mountain district, Wyoming has some pyrope garnet and picroilmenite and looks more like scoria than kimberlite
IG3 Kimberlite from Iron Mountain. Another tuffaceous kimberlite.
The Ferris 2 kimberlite from Wyoming.
Large fractured chromian diopside (chrome diopside gemstone) megacryst in Sloan 2 kimberlite from Colorado.
Gemstones like this are typically not recovered from diamond mines even though they are as beautiful as any emerald.
Kimberlite from the Victor pipe in Canada.