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Platinum group elements, why layers - Coggle Diagram

- - - - resistant to corrosion/oxidation
      - stable at high temperatures
      - melting point >> gold
        
        solid unless temp very high
        
        precipitate early from magma chamber
      - high melting point
      - siderophiles
        
        bonds with iron and sulphides
  - - - Run, Road, Pd, Ostrich, Iran, Pitta (think of running on a road in iran full of ostrich eating pitta and getting paid)
      - ru, rh, ir, os, pt, pd
- - - - pure PGE mineral inclusions
- - - - cool as they rise upwards
        
        minerals with highest melting temperature crystallise first (PGEs inc)
        
        settle under gravity into magma chamber
        
        means PGEs are not found in lava flows as they settled early
        
        for silicate minerals fractional crystallisation process means mafic higher crystalisation temperature (olivine,pyroxene)
  - - - sulphide becomes less soluble as temperature decreases
        
        affects temp of precipitation and zone of dense mineral formation
        
        sulphide dense
    - - magma chamber reacts with pyritic black shale
        
        can make more PGE as sulphide contains PGE
        
        taken from magma chamber into mineral structure
        
        more scavenging material with more sulphur so more PGE collected
- - - - pulsing pattern of settling of crystals
      - layers different compositions - not all PGEs
      - gabbro, basic, basaltic, iron and magnesium
        
        mafic to ultramafic
    - - pyroxenite - dark colour (chromite, olivine)
      - Hazburgite (type of igneous rock)
      - big = evolution of magma chamber
    - - merensky reef
        
        critical zone
        
        layers of igneous rock enriched in PGEs
        
        mined to depletion
      - UG2
        
        critical zone
        
        thinner
        
        lower grade than merensky
      - small = local changes in magma chamber as rock evolved and cooled