Mineral crystals, coloured scanning electron micrograph (SEM). This view shows different microcrystals of different origin. This sample is from the Clara Mine, in the Oberwolfach district, in the Black Forest, Germany. This mine is famed for the large number of minerals (more than 375) found here, some of which are very rare. Large amounts of baryte and fluorspar are mined here. Magnification: x4700 when printed at 10 centimetres across.