the lufwanyama emerald series, part twenty-four: the depth question
the kagem chama open pit currently mines to approximately 130 metres depth. the documented mineral resource stands at 1.8 billion carats of emerald and beryl at an in-situ grade of 281 carats per tonne. that is the documented resource within the current mining envelope — the volume of rock drilled, sampled, and modelled in sufficient detail to support a resource estimate.
the current mining envelope extends to approximately 130 metres. the kafubu area contains approximately 19 documented emerald deposits across a productive zone of approximately 200 square kilometres. the geological formation that hosts the mineralisation — the pan-african metamorphic and metasomatic system — is a regional geological feature. it does not stop at 130 metres because that is where the current pit ends.
the emerald-bearing contact zones in the kafubu belt are steep to sub-vertical features that persist at depth. steep, sub-vertical ore bodies are among the most economically favourable geometric configurations in mining because they maintain grade and width at depth without the geometric dilution that affects shallow-dipping systems.
a 4-metre wide contact zone carrying good emerald grades at 130 metres is, under the right geological conditions, still 4 metres wide and carrying good grades at 200, 300 metres, or deeper.
the kafubu emerald system has not been tested at the depths that would allow a definitive assessment of its vertical extent. the drilling programmes that gemfields and other operators have undertaken are primarily aimed at resource definition within the current mining envelope — not at testing the deep extensions of the system.
the 1.8 billion carat documented resource at kagem — extraordinary as it is — is almost certainly not the full story of what the kafubu belt contains. the depth extensions, the lateral extensions across the 200-square-kilometre productive zone, and the other licence areas represent a potential resource that dwarfs what has been mined in the 40-plus years since the modern kafubu emerald industry began.
most of the kafubu emerald resource is still in the ground.
and most of it is still below the level that any drill bit has yet reached. 💚