This geological formation represents a localized swelling where mineral-bearing fluids pooled and crystallized in a large cavity or structural trap. Instead of following a narrow, predictable planar path like a typical vein, the deposit balloons into a discrete, rounded body. These formations can yield high tonnages of ore over a very short distance.
Heard on the job
The drill core shows the narrow quartz stringer opening up into a massive bunny of solid galena just past the fault.