By kind invitation of Professor John Gurney, 25 club members visited Mineral Services on 24th February to see his exceptional exhibition “Messengers from the Mantle”. This irreplaceable collection of kimberlites was initially created for the 35th International Geological Congress at the Cape Town International Convention Centre in September 2016, and was displayed again at the 11th International Kimberlite Conference in Gaborone, Botswana in September 2017.

Kimberlite rocks are known for bringing up diamonds from deep in the mantle to the surface of the Earth, but they also provide scientists with important clues to the composition of rocks deep in the Earth below the lithosphere. Rocks from the Mantle Room collection at the University of Cape Town were selected for this exhibition, and many were sawn into very thin slices by our own Henri Schram. After sawing, the slabs were glued onto glass, polished even finer, mounted in display stands of lazer-cut steel echoing the shape of the section, and lit from behind. John Gurney and Phil Janney from UCT showed us around. Photos below show and describe a little of what we saw.

Dr Phil Janney explaining the contents of the showcases

John Gurney is seen here setting up the specimen shown on the right for us to look at. It shows evidence of having been a surface rock in its way distant past, which then was subducted back down into the mantle, only to return to the surface again in a kimberlite pipe bringing diamonds with it

The small photos are thin polished sections of different examples of kimberlite

Composition of kimberlite

John has also created a craft beer brewery and restaurant at the back of his premises. Some of our group moved on there after viewing the exhibition to taste the beer and chat further with John and Phil

Our special thanks go to John Gurney and Henri Schram for setting up this outing for us, and to Annette Schram for the following photos

Henri and John Gurney

Henri admiring some of his polished rock slices

Some of the ladies who attended

The library now has for loan a copy of the book “Barren Lands” by Kevin Krajick. This book details the hunt for diamonds in Canada, and the large part that John Gurney played in this.

“... the global intrigues and daunting natural forces facing protagonists Charles Fipke and Stewart Blusson as they race against the mighty DeBeers cartel in the 1990s, this is the definitive account of one of the world’s great mineral discoveries. It is also a tale of supreme adventure, taking the reader into a magical – and now fast-vanishing – wild landscape.”   First come, first served!

If you are interested in learning more about kimberlites and how they formed, see also

Or watch these short videos