Leicester scientists discover precious metals in Mordor

Two geologists from the University of Leicester have found gold, along with copper, tellurium and other metals in a geological locality in Australia, referred to as the Mordor Igneous Complex - named after its uncanny resemblance to the location from the Lord of the Rings trilogy. 

Complete with its own Mount Doom, the Mordor complex is a remarkable geological feature in the centre of Australia, where erosion has produced a three-sided box-shaped canyon, almost identical to that of Mordor in JRR Tolkien’s Lord of the Rings books. 

Associate Professor Dr David Holwell and PhD researcher Daryl Blanks from the Centre for Sustainable Resource Extraction have revealed the gold, tellurium and copper rich nature of the mineralisation around the edges of the Mordor Igneous Complex for the first time. In particular, they found how the metal rich sulphides were associated with carbonate minerals. 

This provides a crucial piece of evidence as to how the metal sulphides are brought to the surface from the Earth’s mantle by volatile-rich magmas, depositing them around the edges of the complex in centimetre-sized globules, or ‘blebs’.

Commenting on the resemblance of the site to Tolkien’s Middle Earth, Dr Holwell said: “It really is quite an incredible geomorphological feature; unique in fact, and visible 50km to the east of Alice Springs on Google Earth if you want to see. 

“The resemblance to Tolkien’s maps led geologists from the Geological Survey to name the area ‘Mordor’, which included naming the highest point of the igneous ring complex as ‘Mount Doom’, and in fact, this is pretty close to where the highest gold concentrations are found.”

On the unexpected journey that the metals have taken, Dr Holwell explains: “Sulphide ‘blebs’ such as those found in the rocks at the margins of the Mordor Igneous Complex shouldn’t be there. They are dense, and when the magmas were generated in the mantle, and were intruded up into the crust, the dense sulphide droplet should sink (like droplets of vinegar in an olive oil salad dressing) and never make it up to the crust at all.”

Co-author on the study, Daryl Blanks, adds: “The carbonate provides a clue as to how the sulphides were transported. Bubbles of relatively low-density CO2 can stick to the sulphides and effectively ‘float’ them up further than would normally be expected, and in this case depositing them around the edge of the intrusive complex.”

This work reinforces the recent discovery by the Leicester team that bubbles of CO2 can physically transport metal rich sulphides up from the mantle, into the crust, potentially forming deposits of metals like nickel, copper, tellurium and platinum-group metals. 

These metals are essential in a number of green technologies vital in transitioning to a low-carbon future. The metals include nickel for electric vehicle batteries, copper for wind turbines, tellurium for solar panels, platinum-group metals for catalytic converters and anti-cancer drugs, as well as gold for jewellery… such as one ring to rule them all.

The article is published in the journal 'Mineralium Deposita'.