Current kimberlite pipe development models strongly advocate a downward growth process with the pipe cutting down onto its feeder dyke by means of volcanic explosions. Evidence is presented from the K08 kimberlite pipe in Venetia Mine, South Africa, which suggests that some pipes or sub- components of pipes develop upwards. The KO8 pipe in pit exposure comprises >90 vol.% chaotic mega- breccia of country rock clasts (gneiss and schist) and <10 vol.% coherent kimberlite. Sub- horizontal breccia layers, tens of metres thick, are defined by lithic clast size variations, and contain zones of shearing and secondary fragmentation. Textural studies of the breccias and fractal statistics on clast size distributions are used to characterize sheared and non-sheared breccia zones, and to deduce a fragmentation mechanism. Breccia statistics are compared directly with the statistics of fragmented rock produced from mining processes in order to support interpretations. Results are consistent with an initial stage of brecciation formed by upward-moving collapse of an explosively pre-conditioned hangingwall into a subterranean volcanic excavation. Our analysis suggests that the pre-conditioning is most likely to have been caused by explosions, either phreatic or phreatomagmatic in nature, with a total energy output of 2.7x109 Id (656 tons of TNT). A second stage of fragmentation is interpreted as shearing of the breccia caused by multiple late kimberlite intrusions and possible bulk movement of material in the pipe conduit related to adjacent volcanism in the K02 pipe.

The Venetia Mine is an open pit operation, mining a diamond bearing kimberlite cluster consisting of a series of pipes and dykes with a vertical displacement. This cluster consists of three kimberlite ore bodies namely K1, K2 and K3 and various satellite ore bodies. The open pit will be mined to a depth of approximately 450m. Waste rock is removed and deposited by means of drill, blast, load and haul technology.

From a depth of below 450m, open pit mining becomes less economical due to the amount of waste rock to be removed. As part of Venetia Mine’s long term strategy, the mine intends to exploit resources deeper than the current open pit horizons by changing the current mining method from an open pit mining process to an underground mining process, utilising caving mining methodologies.

The ore is hauled to the main treatment plant where it is processed and diamonds are liberated through crushing, scrubbing, screening, dense media separation and x-ray processes. The main treatment plant produces and deposits two major waste streams, namely course and fine tailings. Venetia Mine activities also include all related engineering support services and infrastructure.