In order to minimise the sampling error and sampling bias associated with the sampling of metal bearing ores it is essential that the heterogeneity characteristics of the ores be fully appreciated. Heterogeneity tests were carried out on the significantly different manganiferous ores produced at Wessels and Mamatwan mines near Hotazel, South Africa, for the purpose of establishing an optimal sampling protocol for the ores. The method referred to as the Segregation Free Analysis (SFA) was used for the determination of the parameters K and Alpha by construction of calibration curves. The method involves crushing a sufficient amount of ore so that after passing it through a set of fifteen nested screens there is sufficient material to then be split into 32 samples of mass 2-5 kg, using a riffle splitter, and analysing each of the samples. Thus, for fifteen nested screens there are fifteen series each consisting of 32 samples, making a total of 480 samples for analysis. Of the eighteen elements that were analysed in each sample only %Mn₃O₄, %FeO, %K₂O, %P, and %SO₂ were calibrated, the first two being the main paying elements and the last three being deleterious elements for the smelting processes in which the ores are used. Calibration curves indicate that for the coarse fraction, above 1 cm, manganese ores have alpha values close to 3, whereas those less than 1 cm in diameter have alpha values closer to 1. Reasons for this behaviour are uncertain but it could be related to the behaviour of the crystal structure in the very pure ores as the ores are progressively crushed and screened to finer size fractions. Separate nomograms were therefore prepared for the coarse and fine fractions. Net conclusions indicate that both Wessels and Mamatwan ores are relatively easy to sample and that simple two or three stage processing will suffice when preparing the final 2 g aliquot at 75 microns. Apart from minor modifications in the sample preparation protocols, there is no evidence to suggest that the Wessels and Mamatwan ores require different sample preparation protocols, or that they should be assayed differently. The calibration curves for manganese ore are compared with the calibration curves for gold bearing ores which generally have alpha values close to 1. The difference in alpha between the gold ores and bulk commodities is considered to be related to the primary distribution of the metals in nature, lognormal for gold and normal for manganese.