Teaching magmatic differentiation as a mechanism for the concentration of ore deposits – a visual approach

Magmatic differentiation is a significant process in the formation of metalliferous ore deposits. It allows for economically viable quantities of sought after minerals to be concentrated into chemically distinct horizons which improves extraction potential. A well-known location demonstrating this is the Bushveld in South Africa, where differentiation has led to the formation of an estimated 72% of global chromite and 88% of global platinum group deposits.¹  Understanding these processes is vital to students taking Geology A-level and is linked to igneous processes, a topic rich in geochemistry and scientific principles that can be challenging to understand as they can't be “seen”. They also link to phase diagrams, the formation of igneous rocks and processes taking place at plate boundaries – all key aspects of the curriculum.  

This poster presentation seeks to visualise an accessible in-class activity which can be offered to students to clearly demonstrate processes such as gravity settling, and the order of crystallisation due to the properties of minerals found in larger bodies of magma. Further activities can then follow linked to the concept of how magmas evolve compositionally over time.  

References: 

• SFA Oxford (n.d.) The Bushveld Complex. Available at: https://www.sfa-oxford.com/lithox/critical-minerals-policy-legislation/all-countries/africa/south-africa/the-bushveld-complex/ (Accessed: 14 January 2026)