The thermal conductivity $K$ of KCL, KBr, fired talc, dunite, and eclogite was measured to pressures as high as 19 kbar and to temperatures as high as 450°C. Fluid pressure was supplied by dry nitrogen. A Manganin resistance gauge and Pt versus Pt-13% Rh thermocouples measured the pressure and temperature, respectively. Data were fitted with the surface $K=\frac{C_1}{(T+T_0)}-\frac{C_2}{(P+P_0)}$ in the sense of least squares by means of a CDC 1604 computer. Conductivities were found to increase nonlinearly with pressure, the slope of the surface decreasing at higher pressures.

• Received 28 February 1967

DOI:https://doi.org/10.1103/PhysRev.161.861