The GeoCore X10 geochemical analysis includes a mineralogical model fit of a user-provided list of potentially present minerals to the observed XRF (X-Ray Fluorescence) and XRT (X-Ray Transmission) signals. Depending on the contents of this mineral list, the fit may include elements 1 to 92 (hydrogen to uranium), except for the noble gases and certain radioactive elements.
Orexplore Insight only shows concentrations for elements detectable by the specific GeoCore X10 model on which the scan was made. Current models can detect elements 13 to 92 (aluminium to uranium), excluding the following elements:
- The noble gases: He, Ne, Ar, Kr, Xe and Rn (atomic numbers 2, 10, 18, 36, 54 and 86).
- Certain radioactive elements: Tc, Pm, Po, Ar, Fr, Ra, Ac and Pa (atomic numbers 43, 61, 84, 85, 87, 88, 89 and 91).
- Some older GeoCore X10 models can not detect Al, Si and P (atomic numbers 13, 14 and 15).
- Au (atomic number 79) detections are only reported by Analysis Software Version 0.4.337 and on (see Scan Information).
- If the XRF signal was degraded during scanning, element concentrations are not available (see Degraded XRF Signals).
Element concentrations data is presented through several views in Insight, as described in the following sections.
Concentrations Plot View
The element Concentrations plot can be found by picking Show → Concentrations from the menu bar. Once enabled, the view is found to the right of the Preview and provides line plotting of down hole element concentrations:
Plotting an Element
To plot the concentration of an element, right-click the plot view and pick the element in the popup menu under Concentrations...:
A new plot curve will appear, in this case a green one showing the concentration of iron:
The legend at the bottom of the view shows the current plot curve color assignments.
Adjusting the Scale
If the plotted element concentrations differ by orders of magnitude, it can be helpful to switch to a logarithmic scale by picking Logarithmic Scale in the right-click popup menu:
The Concentrations Map view, available under a tab next to the 3D Tomography view, provides a gray scale intensity map showing the logarithmized concentration of all measured elements:
High concentrations are shown in black while low concentrations are light gray. Columns are ordered by atomic number. Hover the map with the mouse pointer to inspect the concentration at a specific spot. In this example, trace amounts of cadmium are picked out in a sphalerite ore zone:
The concentration map is useful as an overview of detected elements, and for identifying geological facies and correlations between elements.
To the far right in the program, a summary of mean concentrations are shown in table format:
The Hole table shows the mean concentrations across the current borehole while the Segment table shows the mean concentrations for the currently selected core segment. The latter is useful when comparing against lab assay data for a specific segment.
Sorting the Tables
The table can be sorted by clicking their headings, for example by concentrations:
For information on how to export the element concentrations to CSV (Comma Separated Values), see Exporting Mass, Density and Concentrations.
As a complement to the results of the mineralogical fit (e.g. element concentrations), Insight also offers the possibility to inspect the XRF signal that is part of the input, as a rawer form of measurement variable.
The XRF Signal plot is enabled by picking Show → XRF Signal from the menu bar, and then appears besides the Concentrations plot. As a companion to the Concentrations plot, the XRF Signal plot uses the same popup menu and selection of shown elements:
The trends of the XRF Signal plot will typically bear a strong resemblance to the corresponding Concentrations, as an increased signal is often linked to an increased concentration. Yet, the mapping from XRF signal to concentration is complex and not always monotonous. The XRF signal may, for instance, be supressed or increased by the presence of other elements, or vary through geometrical factors that depend on the position, shape and integrity of the scanned drill core.
The XRF Signal is therefore by no means a substitute for the Concentrations, but rather a complement offered for more detailed inspections.
The XRF Signal is presented on an undisclosed relative (unit less) scale, which is unique for each available element, and subject to change without any form of notice. It should therefore never be relied upon as e.g. a measure of element concentration, or be used for arithmetical operations such as ratios between different elements.
Degraded XRF Signals
The standard sample holder used during GeoCore X10 scanning is a tube constructed out of carbon fibre reinforced epoxy. The tube wall is densely perforated to permit largely unobstructed XRF measurements of the drill core surface. The standard holder can be used for the vast majority of drill core qualities.
|Standard Sample Holder|
In addition to drill core, the GeoCore X10 can scan unconsolidated materials, soils, chips and heavily fractured/friable drill core. To permit scanning of these types of materials without it escaping through the sample holder perforations or compacting during scanning, either a special solid-walled sample holder must be used, or the material placed into smaller solid-walled inner sample holders which are in turned placed in the standard sample holder.
|Solid Sample Holder||Standard + Inner Sample Holder|
As XRF signals are inevitably obstructed for scans performed with solid-walled containers, results for material scanned in anything but the standard sample holder are considered XRF degraded. Results from the mineralogical model fit (element concentrations and high-resolution estimated densities) and the XRF signal plot are unavailable for XRF degraded sections, whereas the 3D tomography and per-sample measured density remains unaffected.