Analytical Suite Metadata
NTGO KIDD indicator mineral re-assignment
Northwest Territories Geoscience Office (NTGO) Kimberlite Indicator and Diamond Database (KIDD) assignment of picked mineral grains
The minerals listed in the Northwest Territories Geoscience Office (NTGO) Kimberlite Indicator and Diamond Database (KIDD) are shown in the table below. There is a good correspondence between these minerals and the six minerals reported by Overburden Drilling Management (ODM) in its standard KIM suite. Correspondence to other reports can be more difficult.
|NTGO KIDD||ODM correspondence||Notes|
|2||Pyrope (peridotitic)||GP||Purple garnet|
|3||Pyrope (eclogitic)||GO||Orange garnet; includes almandine in addition to pyrope|
|4||Total garnet||3 + 4|
|5||Chrome diopside||DC||Distinctly emerald-green; low Cr diopside is a paler green.|
|7||Ilmenite, picroilmenite||IM||Picroilmenite is Mg-rich ilmenite|
|9||Olivine||FO||Forsterite is the magnesium end-member of the olivine solid solution series|
|10||Total Grains||1 + 2 + 3 + 5 + 6 + 7 + 8 + 9|
Mapping of grain counts from the original reported data to the NTGO KIDD suite helps to ensure a consistent approach when comparing KIM counts across different surveys.
Published KIM data do not generally correspond precisely to the ten KIDD categories. Complexities arise because the publication may list:
- Grain counts based on visual identification
- Grain counts based on electron microprobe analysis
- A combination of visual and electron microprobe identifications
In order to compare KIM data across different surveys, the reported grain identifications should be re-assigned to a standardised suite. Re-assignment must be done on a survey-by-survey basis.
An additional complication is that many KIM counts involve estimated numbers of grains based on visual identification of only a fraction of the HMC concentrate. If only a subset of the candidate KIM grains are analysed by microprobe, it becomes very difficult to revise candidate KIM counts (based on visual identification) to confirmed KIM counts (based on microprobe analysis).
The weight of sample that was processed by the laboratory prior to picking the indicator minerals should also reported, where known. Ideally, indicator mineral counts should be normalized to a standard sample weight. When comparing across different sample media and surveys, variations in (a) the nature of the material collected (e.g. till vs. esker vs. stream sediment), (b) field sampling procedures, and (c) laboratory sample preparation procedures (e.g. sieving to different grain sizes) should also be taken into consideration.
Two weights are included in the suite:
- The table feed weight (in kg) – the < 2 mm size fraction of the original bulk sample, that is processed to obtain the heacy mineral concentrate
- The weight (in grams) of the 0.25-0.50 mm size fraction of the non-ferrous heavy mineral concentrate
Sample material: solid
Sample weight: unstated
|Index||Method Order||Method ID||Quantity||Detection Limit|
Associated Analytical Packages:
|Index||Package ID||Package Name|
|1||248||NTGO KIDD remapping|
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