Where to find Diamonds? 💎

Ever wonder where and how does "girl's best friend": DIAMOND occurs?

Well, there are synthetic and naturally occurring diamonds. Synthetic diamond, those of artificially made in laboratories and those of naturally made by geological processes.

Being a geologist, what excites us more is how and where does it occurs naturally, right?

If you remember, there are different kinds of ore deposits, there are epithermal high-sulfidation, epithermal low sulfidation, skarn and so onnnnnnn (one blog post is not enough to discuss it all, so you may browse your college notes just in case).

Then there is a Magmatic Segregation Deposit whereby mineral deposits are formed by direct crystallization and concentration from the magma. It may occur as strata-like segregations, as dissemination and as vein-like injection. (Believe me, there are so many scenarios in this deposit, I advice you to get your notes now).

So how does these all relate to diamond?

Kimberlite Diatreme Illustration from Colorado Geological Survey

If a kimberlite magma passes through diamondiferous portions of the mantle, it may sample and bring diamonds to the surface provided they are not removed during ascent. The rapid degassing of carbon dioxide from the magma near surface produce fluidized intrusive breccias (diatremes) and explosive volcanic eruptions.

Kimberlite is a potassic, ultramafic rock dominated by olivine and other mantle phases often including diamond.

Diamonds in kimberlites occur as sparse xenocrysts and within diamondiferous xenoliths hosted by intrusives.

(Still with me guys?)

Distribution: Kimberlites occur in continental settings and range in age from late Proterozoic to Recent. The greatest concentration, however, is in rocks of Mesozoic age. Kimberlites have been found on all continents, but the largest concentration is along the East African Rift System. Surprisingly, diamond pipes also occur in North America in Arkansas and Wyoming-Colorado.

Economic concentrations of diamonds occur in approximately 1% of the kimberlites throughout the world.

Distribution of kimberlites worldwide in relationship to Archaean cratons. While this diagram shows a good correlation between cratons and kimberlites, it also highlights the large areas with unknown or undocumented potential. Also note that this doesn’t include a number of more recent discoveries. (From the MINEX Exploration Newsletter No. 22 originally adapted from Geology of Canadian mineral deposit types O.R. Eckstrand et al, 1995, Geology of Canada No. 8, Geological Survey of Canada.) (source: https://www.geologyforinvestors.com/search-diamonds-introduction-kimberlite-exploration/)

Ore mineralogy: Diamond

Gangue mineralogy: Olivine, phlogopite, pyrope and eclogitic garnet, chrome diopside, magnesian ilmenite, enstatite, chromite, carbonate, serpentine

Kimberlite with diamond as xenocryst; sample from Dr. Yolanda Aguilar of MGB Central Office.

Diamond xenocryst. From www.geologyforinvestors.com

There you go, I hope this short topic about kimberlite and diamond helps you appreciate geology more (and your college notes as well).