The problem of estimating the proportion of lithological (ore) types i
n volumes of mineral deposits is considered when an auxiliary variable
Z(z) is observed along with the lithology L(x) at x. The process {Z(x
)} is assumed to be stationary and an assumption on the statistical re
lationship between {Z(x)} and {L(x)} processes is made. Consequently,
the second-order stationarity of {L(x)} is not required. A method usin
g the kriged distribution of the auxiliary variable is proposed. A cas
e study illustrating the procedure is given.