## 4 Results
The density plot of the complete dataset with no SWIR masking (Figure 3) outlines the general composition and placement of key locations within the iron boomerang. Each end of the iron boomerang contains what are essentially spectral endmembers with the hematite endmembers located around an Fe oxide wavelength of 870 nm and Fe oxide FWHM of approximately 140 nm, while the vitreous endmembers can be located approximately at a Fe oxide wavelength of \(>\)980 nm and Fe oxide FWHM of \(>\)370 nm. The location of the three endmembers were identified and confirmed with characterised laboratory samples and from a visual and spectral examination of the core at the locations where endmembers were identified. The visual and spectral examination consisted of visually inspecting the physical samples identified as endmembers and confirming the VIS/NIR/SWIR spectrum of samples were consistent with known endmembers from a spectral library for hematite, ochreous and vitreous goethite. From the hematite endmember location in Figure 3, as the iron boomerang is traversed from left to right and bottom to top, the proportion of hematite to goethite decreases toward the more goethite-dominated region (a Fe oxide wavelength greater than 920 nm). Within the goethite-dominated region and as the Fe oxide FWHM increases, a move from more ochreous goethite to greater proportions of vitreous goethite is observed. At Fe oxide FWHM values greater than 370 nm, the bulk of the samples are found to primarily vitreous goethite, while in the absence of kaolinite, the bottom edge of the goethite region (yellow ellipse) tends to be dominated by ochreous goethite. The samples affected by kaolinite are found to be spread throughout the entire iron boomerang but samples that have deep kaolinite features (high quantity) can be found below the main iron boomerang (red ellipse). The densest portion of the goethite region within the iron boomerang is comprised of mixed ochreous and vitreous goethite (brown ellipse) and may be more representative of brown goethite. Plotting the iron boomerang for the diamond core-only dataset (Core 1) with SWIR masking in place and manually selecting several key regions of interest (ROI) demonstrates the typical spectral signatures associated with those ROIs within the iron boomerang (Figure 4A). The selection of the ROI is purely based on observable regions of change in the iron boomerang or regions where it terminates. As previously noted, the general hematite and goethite trend can be mapped via the hematite goethite ratio [5] but is revealed in greater detail within the iron boomerang and perhaps shows that the actual hematite-goethite ratio will vary depending on the goethite type. The spectra associated with the  
Figure 3: The density plot of the complete dataset with no SWIR masking is shown and outlines the general composition and placement of key locations within the iron boomerang. At each end are two spectral endmembers comprised of hematite around a Fe oxide wavelength of 870 nm and Fe oxide FWHM of approximately 140 nm and vitreous goethite located approximately at a Fe oxide wavelength of >980 nm and Fe oxide FWHM of >370 nm. As the iron boomerang is traversed from left to right and bottom to top the proportion of hematite to goethite decreases toward a more goethite-dominated region at wavelengths greater than approximately 920 nm. As the Fe oxide FWHM increases within the goethite-dominated region, a move from more ochreous goethite to greater proportions of vitreous goethite is observed. At Fe oxide FWHM values greater than 370 nm, the samples are found to be primarily vitreous goethite, while the bottom edge of the goethite region (yellow ellipse) tends to be dominated by ochreous goethite in the absence of kaolinite. The densest portion of the goethite region within the iron boomerang is comprised of mixed ochreous and vitreous goethite (brown ellipse) and may be more representative of brown goethite.