Gold deposits estimation using indicator kriging

CIM Bulletin, Vol. 83, No. 934, 1990

K. Fytas, N.-E. Chaouai and M. Lavigne, Universite Laval, Quebec City, Quebec

Indicator kriging is one of the nonparametric geostatistical techniques, ideal for estimating the reserves of irregular mineralizations (e.g. gold, uranium, platinum, diamonds, etc.). Such mineralizations are characterized by variograms which are very sensitive to extreme values (outliers) and very difficult to model. The classical approach to this problem in the industry is to trim off these high grades using arbitrary empirical upper limits established either from practice or subjectively. Contrary to this simplistic approach, indicator kriging discretizes the histogram of the grades (usually log normal) in several classes and carries out interpolation separately for each class. This paper gives an overview of the differences between ordinary and indicator kriging along with the steps required to carry out indicator kriging. The paper concludes with a case study involving a gold deposit estimation.

Mots Clés: Gold deposits, Geostatistics, Indicator kriging