The other major source of iron problems is Mafic material. This...

The other major source of iron problems is Mafic material. This is a term used to describe rocks rich in iron and magnesium. Examples include olivine, biotite, hornblende and pyroxene. I don't have a clue which one is below but google also tells me:



So when we have a sample like DD core below is TGRCD0024: 3.6m @ 1.11% from 171.6m. Its basically very high iron readings in Mafic material and low iron readings in the pegmatite. The pegmatite itself may be well under 1% but a crushed up blend of the whole tray could be nearer 4-5% iron. This creates a mining problem and if it works well, gains from an ore sorter.

How would you mine this?
Option #1 - Remove all the Mafic above the seam and probably some of the pegmatite. The 3.6m seam effectively shrinks in width but you avoid high iron material
Option #2 Remove as much Mafic material as practical, mine the Spod, process the spod and use the metalic properties of the iron in Mafic to get the iron ore grade down.
Option #3 Remove as much Mafic material as practical, use an ore sorter to remove any further identifiable Mafic material and process the rest (via DMS or Flotation).