Abstract: | An apparatus to generate high pressure up to 12000 kp · cm−2 and a microhardness device to be put in it are described. The pyramid identations originate from the moving force of the falling indenter. To compare microhardnesses at normal and high pressure the viscosities of the pressure fluids are assimilated. For that purpose the microhardness device served as viscosimeter. With extrapolated falling height zero of the idennter and a load of 36 g the (001)-surface of Baryt single crystals have a microhardness of about 210 kp · mm−2 at a hydrostatic pressure of 10000 kp · cm−2. The corresponding microhardness at normal pressure is 90 kp · mm−2 |