environmental material refractory astrogeological material Add and axiomatise with moon and lunar crust envoAstro A material which is composed primarily of chemical elements and compounds which have equilibrium condensation temperatures above approximately 1300 Kelvin and which are part of the crust or atmosphere of a moon or planet. The refractory group includes elements and compounds like metals and silicates (commonly termed rocks) which make up the bulk of the mass of the terrestrial planets and asteroids in the inner belt. refractory material