It is valued for its heat and electrical conductivities, ductility, malleability and resistance to corrosion. Mixtures may have variable thermal conductivities due to composition. Other advantages include high electrical and thermal conductivities, high strength, high hardness. Higher conductivities are associated with larger anions, such as tosylate. Values of thermal conductivities for various materials are listed in the list of thermal conductivities. Solid rock surfaces, such as outcroppings, have high thermal conductivities and inertias. Real heads are non-spherical and have largely anisotropic conductivities (particularly white matter and skull). The thermal conductivities of common substances span at least four orders of magnitude. Different rocks, sediments and geological structures have a wide range of different electrical conductivities. Nafion can be manufactured with various cationic conductivities. Fluids having conductivities above 50 pS/m are called non-accumulators. His work focused on the conductivities of electrolytes. They can be polished to a metallic luster because of their excellent electrical conductivities. The Group IV and V dichalcogenides attracted attention for their high electrical conductivities. Doping of either "cis"- or "trans"-polyacetylene leads to an increase in their conductivities.