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

General Methodology:

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
1 Diamond    
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.
6 Chromite CR  
7 Ilmenite, picroilmenite IM Picroilmenite is Mg-rich ilmenite
8 Orthopyroxene    
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

Instrument: unstated

Sample material: solid

Sample weight: unstated

Analytical Technique:

Hierarchical classification

Technique >> Physical techniques >> Mineral identification >> Visual >> Binocular microscope



Analytical Decomposition:

Hierarchical classification

Decomposition >> None



Analytical Methods:

IndexMethod OrderMethod IDQuantityDetection Limit
1  6296     Wt_TblFeed 
2  6325     Wt_HMC_025_050 
3  6297     Diamond 
4  6298     Pyrope_P 
5  6299     Pyrope_E 
6  6300     Total_Garnet 
7  6301     ChrmDiop 
8  6302     Chrom_Spin 
9  6303     Ilmn_Picro 
10  10  6304     OPX 
11  11  6305     Ol 
12  12  6306     Total_Grains 

Associated Analytical Packages:

IndexPackage IDPackage Name
1  248     NTGO KIDD remapping
Date modified: