AbstractThe results of studies in the high‐alumina portion of the system BeO‐ Al2O3do not agree with those of previous workers. An X‐ray study of sintered and fused mixtures in this portion of the system indicates the existence of a hitherto unrecognized compound intermediate between chrysoberyl (BeO‐ Al2O3) and corundum (Al2O3) and possessing the probable formula BeO‐3 Al2O3. The new compound is optically almost identical with chrysoberyl but gives a decidedly different X‐ray pattern. Discussion and criticism of earlier work are presented with the aid of equilibri