(IDEX Online) - Petra Diamonds has been fined 1bn Tanzanian shillings ($429,000) over the breach of its tailings dam at its Williamson mine.Its holding company Williamson Diamonds Limited (WDL) has been ordered to pay sum to the Tanzanian government's National Environment Management Council (NEMC).Dr Samuel Gwamaka, director general of the NEMC said WDL was responsible for compensating victims of the tailings storage facility (TSF) breakage in November.Homes were damaged as 12.8m cubic metres of muddy water and tailings material covered an area of over 5km2.Petra, which has a 75 per cent holding in the mine, said in a statement that it was "engaging constructively with the Tanzanian authorities in respect of the cause of the incident".It said: "The root cause of the subsidence that led to the breach has not yet been determined and requires a forensic geotechnical investigation to be completed to do so."Petra doesn't expect to resume mining operations at Williamson until "the middle of 2023".Pic courtesy Petra Diamonds