This International Standard specifies experimental methods for the evaluation of quality variation of iron ores for each type of iron ore being traded and for each handling plant. Two distinct approaches are specified. The first is to analyse interleaved samples composed of a number of paired increments taken and combined alternately following stratified sampling or systematic sampling as specified in ISO 3082. The second is to collect and analyse individual increments and then to analyse the data using variographic methods. Using interleaved samples involves less work, but use of variograms provides a better estimate of quality variation and hence a better estimate of the sampling variance. The variogram method is usually used to fine tune a sampling operation. NOTE The experimental methods may be applied approximately to time basis sampling when the flowrate is almost uniform.