Gemfields, the London-listed majority owner of Montepuez Ruby Mining (MRM), says it is co-operating with the Mozambican authorities to investigate videos apparently showing the torture of informal, artisanal miners, known as ‘garimpeiros’ on the MRM mining concession in northern Mozambique. The disturbing videos were posted to Facebook by Mozambican investigative journalist Lázaro Mabunda on 17…...