## 4 Results
left most portion of the iron boomerang and is, as expected, comprised of pure hematite samples (Figure 4B) while those located at the right hand most side of the iron boomerang are comprised of pure vitreous goethite (Figure 4C). The region labelled as mixed goethite (Figure 4D) in Figure 3 shows the difference in shape of the Fe absorption feature as compared to Figure 4C and the reduction in visible absorption features between 1500 and 1850 nm. Pure ochreous goethite does not exhibit the drop off observed at approximately 1300 nm (Figure 4C,D). Mixtures of hematite and  
Figure 4: The iron boomerang for the diamond core-only dataset (Core 1) with SWIR masking in place and selecting several key regions of interest (ROI) is shown in (**A**) and coloured by the Fe oxide depth. Figure (**B–G**) show the hull-corrected spectra. (**B**) is the left most portion of the iron boomerang comprised of hematite samples. (**C**) and located at the right hand most side of the iron boomerang are primarily vitreous goethite. (**D**) represents a region of mixed ochreous and vitreous goethite. (**E**) is generally purer ochreous goethite and does not exhibit the drop off observed in (**C**) and (**D**) from approximately 1300 nm. (**F**,**G**), respectively, show mixtures of hematite and goethite with at least two different goethite types (vitreous and ochreous, respectively). vitreous goethite are observed (Figure 4F) whereas a mixture of hematite and ochreous goethite is shown in Figure 4G. It is noted though that no seemingly strict separation, except for the leading edges of the iron boomerang beyond Fe oxide wavelengths of approximately 930 nm, is evident at this stage between ochreous and vitreous goethite. Figure 5 are the alteration-masked iron boomerang metrics for each of the individual data sources using a density plot for better visual comparison as noted in Figure 2B. Figure 5A is the Rocklea Dome CID RC chips set with 1089 samples, Figure 5B-D are for the Hamersley Basin BIF RC chips sets with 966, 2124, and 756 samples, respectively, Figure 5E is the Hamersley Basin BID pulp dataset comprised of 5423 samples and Figure 5 FG are the Hamersley Basin diamond core datasets with a total of 19,267 and 9323 samples, respectively. The separation of the individual datasets allows the general makeup of the individual datasets to be quickly and reasonably established. The CID dataset is found to be primarily composed of goethite and has very little hematite, resulting in overall high Fe oxide wavelength and Fe oxide FWHM (Figure 5A). For the BIF chips on the other hand, the trend is opposite as it is composed of a greater proportion of hematite with some hematite/goethite mixtures but far fewer goethite only samples, indicated by lower Fe oxide wavelength and Fe oxide FWHM values when compared to the CID. Figure 5B,C suggest a similar presence of hematite and hematite/goethite mixtures, with Figure 5C exhibiting a greater proportion of potential vitreous goethite, as evidenced by the samples with Fe oxide FWHM values above 360 nm and Fe oxide wavelengths beyond 1000 nm. Figure 5F, G from the two core datasets are very similar in distribution and suggest a greater amount of mixing and similar assemblages, with Figure 5F showing a greater amount of long Fe oxide wavelength vitreous goethite samples. Note the greater amount of data (9000+ samples) in the diamond core iron boomerangs are primarily due to the far higher downhole sampling by the HyLoggerTM, with approximately 100 samples per metre. Lastly, the iron boomerang applied to the Hamersley Basin BID pulp samples shows that the distribution would appear to show a heavy concentration of hematite and smaller amounts of hematite/goethite mixtures with the goethite being predominantly ochreous due to the Fe oxide FWHM being below 350 nm (Figure 5E). However, in this case, the distribution is affected by the nature of the sample media itself.