Friability of rocks and ores can be determined by brittleness tests. A test apparatus to determine friability value has been designed to suit limestone strength characteristics used in cement production. The friability values of barite, marble, limestone and bauxite have been determined and compared with the corresponding Bond work index (W-i) and grindability index (G) of these materials. The physico-mechanical properties of the tested materials have also been determined to investigate their effect on friability and grinding. The relationships obtained between the indices were in surprisingly good agreement, with high correlations (0.99 and 0.97). The Bond work index and the grindability index can therefore be estimated from the friability value, which can be determined more rapidly than from the Bond test. (c) 2005 Elsevier Ltd. All rights reserved.