The first quotient (RQD.-Jn). representing the st1'ucture of the rock mass. is a crude
measure of the block or particle size. with the two extreme values (100."'O.5 and
10.520) differing by a factor of 400. If the quotient is interpreted in units of
centimetres. the extreme ‘particle sizes‘ of 200 to 0.5 cm are seen to be ciude but
fairly realistic approximations. Probably the largest blocks should be several times
this size and the smallest fragments less than half the size. (Clay particles are of
course excluded).