FILE PHOTO: A general view shows a cassiterite and tantalum ore in a semi-industrial mineral processing plant in Gatumba in western Rwanda, November 25, 2009. REUTERS/Hereward Holland/File Photo
FILE PHOTO: A general view shows a cassiterite and tantalum ore in a semi-industrial mineral processing plant in Gatumba in western Rwanda, November 25, 2009. REUTERS/Hereward Holland/File Photo