In many hot mines a large portion of the total heat load is associated with the surrounding strata. In order to maintain acceptable underground environmental conditions, the mine heat load must be controlled by the ventilating airstream, and in certain cases by mechanical refrigeration. To compute existing, or future heat additions from the surrounding rock, certain parameters must be -determined. These parameters include the rock thermal conductivity, thermal diffusivity, and the geothermal gradient (with relation to a virgin rock datum). These rock thermal parameters are typically estimated from published literature, or evaluated by laboratory or in-situ measurements. Presented in the paper are the results from a series of tests conducted at Hecla Mining Company\u27s Lucky Friday Mine. These tests include in-situ measurements of rock thermal conductivity and geothermal gradient, which were performed in highly active sections of this deep silver mine. The results from the in-situ tests are compared with data obtained from laboratory testing of mine core samples. The methodology, measurement equipment, test data, and main results are described
