Exploration for diamond and other deposits using indicator mineral studies

Quaternary deposits, most importantly glacial till, represent sedimentary materials derived directly from the bedrock that have been transported in the glacial flow direction. The till therefore contains a mineralogical record of all of the rock types the ice has encountered. What is important for exploration is that some amount of these mineral grains in the till are unique to certain host rocks and their ore deposits. For example diamonds, carbonatites, PGE-mineralization, gold, Li ores and some gemstones are each associated with their own distinctive suite of indicator minerals (gold of course is its own indicator). The key innovation that is required for this type of exploration is the ability to find and recognize all important indicator minerals amongst the many trillions of grains in a given sample, something that requires detection limits on the order of a few ppq (part per quadrillion).

An example of exploration Method for diamonds:

• Sampling of basal till
• Preconcentration of heavy minerals
• Final concentrate by heavy liquids
• Handpicking and SEM checking of interesting grains
• Further studies
  - Microprobe major and trace element studies
  - Mantle pressure temperature
  - diamond potential 

Links to contents/services related to the subject:

 Diamond page
 Electron optics and microanalysis

Contact our experts:

Senior Scientist Hugh O'Brien, hugh.obriengtk.fi