A mine collapse on Tuesday at a major coltan mining site in eastern Congo left at least 200 dead, according to Congolese authorities, a number disputed by the rebel group that controls the mine.The collapse took place Tuesday at the Rubaya mines, which are controlled by the M23 rebels, according to a press release from the Ministry of Mines on Wednesday.Fanny Kaj, a senior official in the M23 rebel group, which controls the mines, disputed the figure and said that the collapse was caused by...