One of the most important aspects of magnesite ore deposits is for assessment of the cutoff grade impurities. The impurities in the magnesite ore deposit with grade higher than cutoff grade is waste, which is sent to the waste dump; the impurities lower than the cutoff grade are sent to the processing plant. The bivariate lognormal distribution will serve as an important tool for analysis impurities. In this paper, the Beylikova magnesite ore deposit impurities in Eskisehir (Turkey) were assessed by bivariate lognormal distribution model. This article presents a procedure for using the bivariate lognormal distribution to describe the joint distribution of correlated SiO(2)% and Fe(2)O(3)% rates of ore deposit. Through the results from the model, it was determined that there are magnesite tonnage rate, mean of SiO(2)% and mean of Fe(2)O(3)% involves the identification of cutoff SiO(2)% and cutoff Fe(2)O(3)%. These analyses are believed to assist the management of magnesite ore deposits and determine priorities to improve mining issues.