All the important thermal properties of rocks can be estimated from the graphs and tables in this report. Most of the useful published data are summarized herein to provide fairly accurate evaluations of thermal coefficients and parameters of rocks for many engineering and scientific purposes. Graphs of the published data on common rocks and minerals were prepared to show the relationships of thermal conductivity with decimal solidity (one minus decimal porosity), water or air pore content, content of certain highly conducting minerals, and temperature. Tables are given of pressure effect on thermal conductivity of minerals and rocks, anisotropy of conductivity, thermal expansion, heat transfer, density, heat generation in rocks, and activation energies of conduction mechanisms in single crystals of minerals. A series of graphs show the specific heats of rock-forming minerals as a function of temperature; with these graphs the specific heat of a rock can be calculated from its mode as accurately as it can be measured. Calculations of conductivity, diffusivity, and thermal inertia of a rock from its mode are described. Discussions of radiative thermal conductivity, radioactive heat generation, and heat transfer in rocks are provided. The best published compilation of thermal conductivities of rocks is in the tables of Clark (1966, section 21). The theory of conduction of heat is described for geologic purposes by Ingersoll and others (1954), and the classic treatise is by Carslaw and Jaeger (1959). The basis for the graphs of conductivity shown hereafter is the finding for vesicular basalt by Robertson and Peck (1974) that thermal conductivity varies as a function of the complement of porosity squared, air or water pore saturation, and content of highly-conducting phenocrysts. Thermal conductivity is given emphasis in this compilation because it is needed in all calculations involving heat conduction in the earth. (An earlier compilation is in Robertson, 1979.) In figures 1-13 the effects of porosity, water content, and quartz, olivine, pyroxene, and clay content on conductivities of most felsic and mafic rocks are shown. Data for other less-common igneous rocks are listed in table 1. Anisotropy data for metamorphic rocks are given in table 2. The effect of temperature on conductivity is shown for the common rocks in figures 14-19 and for rock-forming minerals in figures 21-26. Conduction mechanisms and activation energies as a function of temperature in mineral crystals and aggregates are considered in the text associated with figures 28 and 29 and tables 3-5; however, the data on conduction mechanisms in rocks are still inaccurate. The available data on the effect of pressure and vacuum on conductivity of rocks and minerals are given in tables 7 and 8. The conductivities of most of the common minerals, both single crystal and polycrystalline, are given in an accompanying open-file report of Diment and others (1988), as well as in Horai (1971) and in Clark (1966, Sec. 21). Thermal expansions (from Skinner, 1966),...

Thermal conductivity measurements at 35°C under 30 bars uniaxial pressure were made on 61 samples of olivine‐bearing basalt with solidity γ (1 − ф, where ф is porosity) ranging from 2 to 98%.Two series of tests were made, one with air and the other with water in the pores. Conductivity varies with γ, the abundance of olivine phenocrysts, and the nature of the pore fluid. From the lowest to the highest γ, the observed conductivities range from 0.2 to 4.3×10−3 cal/cm s °C for samples with air in the pores and from 2.0 to 5.8×10−3 cal/cm s °C for samples with water in the pores. Differences in vesicle size in samples of the same total porosity do not affect the thermal conductivity. The measured conductivities were compared with values calculated on the basis of 11 theoretical models and combinations using conductivities of air and water and a reasonably well determined conductivity of fully solid basalt. For air‐saturated samples the values calculated by several models compare well with observed values for samples with solidity of <0.9. Samples with high solidity have measured conductivities appreciably less than the conductivity determined for fully solid rock; in olivine‐poor samples the difference is 40%. For water‐saturated samples the measured values also are less than the value for solid rock, 15% less for olivine‐poor samples. We postulate that the difference between observed and calculated conductivities for both air‐ and water‐saturated samples is due to the insulating effect of micropores and thin microfractures that were formed during initial cooling of the volcanic samples; these micropores and microfractures were not completely filled with water during our measurements of water‐saturated samples. In still‐cooling newly formed lava the microfractures will not yet have opened, and the conductivity of the lava may be higher than what would be predicted from our measurements. When empirical correction factors are used to account for the insulating effect of the microfractures and micropores, the conductivity of basalt can be predicted by two models. When the mean of the parallel and series models is used, the conductivity of both air‐ and water‐saturated samples can be predicted within 0.3×10−3 cal/cm s °C from the mineral and pore fluid compositions, conductivities, and proportions. With a quadratic model the values for the square root of conductivity form linear plots against solidity, requiring only the porosity and abundance of olivine phenocrysts of Hawaiian basalts to estimate conductivity within 0.2×10−3 cal/cm s °C.

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Shear and longitudinal velocities were measured by the ultrasonic phase comparison method as a function of pressure to 8 kbar on synthetic glasses of basalt, andesite, rhyolite, and quartz composition and on natural obsidian. Velocities of most of the glasses decrease anomalously with pressure, but increasingly more‐normal behavior occurs with decrease in SiO2 content. The pressure derivatives of rigidity and bulk modulus increase linearly, from −3.39 to −0.26 and from −5.91 to +2.09, respectively, with decrease in SiO2 content from 100 to 49%. The change from negative to positive in the pressure derivatives of both moduli and observed at Poisson's ratio of about 0.25 is consistent with the Smyth model for the anomalous elastic behavior of glass. If the temperature in the upper mantle is about 1500°C, tholeiitic basalt would be molten in accordance with the partial melt explanation for the low‐velocity zone; at 1300°C and below, basalt would be in the glassy state, especially if more felsic than tholeiite. At a temperature of 1370°C and at 30 kbar, reasonable values for the upper mantle at 100 km depth, the basalt glass of this study would have a viscosity of about 1013 P. On the basis of the theory of viscoelasticity the glass would support shear wave propagation at frequencies above 0.1 Hz. Under such conditions of PT, 10 to 30% basalt glass in a matrix either of eclogite or olivine would reduce the seismic velocities by 3 to 9% and could also account for the values observed in the low‐velocity zone.