Showing, Anomalous and Significant Thresholds for Metallic Substances in the SIGÉOM

Table of Showing, Anomalous and Significant Thresholds

Code	Description	Unit	Significant threshold	Anomalous threshold	Showing threshold
Ag	Silver	ppm	5	15	50
Au	Gold	ppb	35	300	1000
Be	Beryllium	ppm	10	100	360
Bi	Bismuth	ppm	5	150	500
Cd	Cadmium	ppm	5	300	1000
Co	Cobalt	ppm	100	1500	5000
Cr	Chromium	ppm	400	2000	6800
Cs	Cesium	ppm	5	150	500
Cu	Copper	ppm	125	500	5000
EGP	Platinum group elements (Pt+Pd)	ppb	70	300	1000
ETR	Rare earth minerals (sum of lanthanides)	ppm	250	1500	1700
Fe	Iron	ppm	110000	200000	300000
Ga	Gallium	ppm	25	60	200
In	Indium	ppm	1	15	50
Ir	Iridium	ppb	100	250	1000
Li	Lithium	ppm	30	300	1160
Mn	Manganese	ppm	1700	30000	100000
Mo	Molybdenum	ppm	5	450	1500
Nb	Niobium	ppm	20	100	350
Ni	Nickel	ppm	150	1500	2500
Pb	Lead	ppm	250	1500	5000
Pd	Palladium	ppb	50	200	500
Pt	Platinum	ppb	20	200	500
Rh	Rhodium	ppb	10	40	100
Sb	Antimony	ppm	10	3000	10000
Sc	Scandium	ppm	50	100	150
Sn	Tin	ppm	10	300	1000
Ta	Tantalum	ppm	5	50	164
Te	Tellurium	ppm	10	75	250
Th	Thorium	ppm	10	200	440
Ti	Titanium	ppm	8000	75000	100000
U	Uranium	ppm	30	300	425
V	Vanadium	ppm	300	700	1400
W	Tungsten	ppm	10	500	1000
Y	Yttrium	ppm	50	250	790
Zn	Zinc	ppm	150	2000	7500
Zr	Zirconium	ppm	250	1000	3700

Showing Thresholds

Showing thresholds for metallic substances were defined in the past to indicate whether one of these substances was of economic interest. In 2023, due to the growing interest in critical and strategic minerals, showing thresholds were added for other elements such as Bi, Cd, Cs, Ga, In and Te. You can find out more about these various minerals on the Mineral Substances Portal.

A rock analysis for a given element with a content greater than or equal to the showing threshold is used to create a mineralized zone record in the SIGÉOM database. A mineralized zone is defined by one or more main substances that meet this criterion. The first main substance determines the zone symbol colour (French) on the interactive map. A mineralized zone may also include one or more secondary substances with contents below the showing value thresholds.

A content considered to be of “economic interest” for a given element, a concept more or less equivalent to a showing threshold, may change over time depending on the market. However, for reasons of consistency, SIGÉOM’s showing thresholds have remained unchanged since their creation. One of the only exceptions is silver, where the threshold has been raised from 5 to 50 ppm in 2023. The 5 ppm threshold was considered too low, which led to the creation of numerous mineralized zone records for geological contexts that were sometimes of little interest. However, silver mineralized zones created before 2023 with a threshold of 5 ppm have not been deleted from the SIGÉOM database. They are still visible on the interactive map by selecting the “Silver (Ag)” layer under the “Metallic substances” theme. It is also possible to access these records via “SIGÉOM à la carte”.

Moreover, prior to 2023, the showing thresholds for gold, copper, molybdenum, lead and zinc were different in the northern and southern parts of Québec. The threshold value was higher in the north of the province than in the south (Grenville, St. Lawrence Platform and Appalachian areas). This difference was explained in particular by better-developed infrastructure in the southern part of Québec, which justified exploration for lower-grade mineralization.

Showing thresholds before 2023
Element	North showing threshold (ppm)	South showing threshold (ppm)
Ag	5	5
Au	1000	500
Cu	5000	1000
Mo	1500	600
Pb	5000	3000
Zn	7500	3000

As of 2023, the showing thresholds were standardized across Québec and only the thresholds defined for the north of the province will now be used to create mineralized zone records in SIGÉOM. As in the case of silver, mineralized zone records created using the old thresholds have not been deleted and remain visible and accessible in SIGÉOM.

Code	Description	Unit	Significant threshold	Anomalous threshold	Showing threshold
Ag	Silver	ppm	5	15	50
Au	Gold	ppb	35	300	1000
Be	Beryllium	ppm	10	100	360
Bi	Bismuth	ppm	5	150	500
Cd	Cadmium	ppm	5	300	1000
Co	Cobalt	ppm	100	1500	5000
Cr	Chromium	ppm	400	2000	6800
Cs	Cesium	ppm	5	150	500
Cu	Copper	ppm	125	500	5000
EGP	Platinum group elements (Pt+Pd)	ppb	70	300	1000
ETR	Rare earth minerals (sum of lanthanides)	ppm	250	1500	1700
Fe	Iron	ppm	110000	200000	300000
Ga	Gallium	ppm	25	60	200
In	Indium	ppm	1	15	50
Ir	Iridium	ppb	100	250	1000
Li	Lithium	ppm	30	300	1160
Mn	Manganese	ppm	1700	30000	100000
Mo	Molybdenum	ppm	5	450	1500
Nb	Niobium	ppm	20	100	350
Ni	Nickel	ppm	150	1500	2500
Pb	Lead	ppm	250	1500	5000
Pd	Palladium	ppb	50	200	500
Pt	Platinum	ppb	20	200	500
Rh	Rhodium	ppb	10	40	100
Sb	Antimony	ppm	10	3000	10000
Sc	Scandium	ppm	50	100	150
Sn	Tin	ppm	10	300	1000
Ta	Tantalum	ppm	5	50	164
Te	Tellurium	ppm	10	75	250
Th	Thorium	ppm	10	200	440
Ti	Titanium	ppm	8000	75000	100000
U	Uranium	ppm	30	300	425
V	Vanadium	ppm	300	700	1400
W	Tungsten	ppm	10	500	1000
Y	Yttrium	ppm	50	250	790
Zn	Zinc	ppm	150	2000	7500
Zr	Zirconium	ppm	250	1000	3700

Some special cases:

Analyses for all platinum group elements (PGE) are rare. In order to compare the mineralized zones with each other, it was decided to calculate the PGE contents by adding only the analytical results for platinum (Pt) and palladium (Pd), which are more commonly analyzed.

Since there is a showing threshold for yttrium (Y) and scandium (Sc), the rare earth elements (REE) are calculated solely by summing the analytical results for the lanthanides (elements 57 to 71 of the periodic table).

To create an iron mineralized zone, a showing content of 300 000 ppm Fe (30% Fe) is not enough. The iron must also be in the form of oxides (not sulphides or silicates). The thickness of the iron oxide layer must also be greater than one metre.

Anomalous and Significant Value Thresholds

These thresholds allow analyses with interesting contents to be targeted quickly. For example, a 0.4 g/t gold content in a sample represents an anomalous value and could be of interest to an exploration company.

Anomalous and significant thresholds were defined on the basis of statistical processing of SIGÉOM’s geochemical database, which totalled 338 089 analyses as of June 2017. No distinction was made as to the origin of the data or the analytical method.

Anomalous and significant thresholds were calculated for the following elements: Ag, Au, Be, Bi, Cd, Co, Cr, Cs, Cu, EGP, Fe, Ga, In, Li, Mn, Mo, Nb, Ni, Pb, Pd, Pt, REE, Rh, Sb, Sc, Sn, Ta, Te, Th, Ti, U, V, W, Y, Zn and Zr.

Anomalous Value Thresholds

The 95th percentile was calculated for each of the above elements from the SIGÉOM database. According to this criterion, 95% of the analyses are below this value and 5% above. Statistically reliable results were obtained for the following elements: Au, Cr, Cu, Fe, PGE,, REE and Rh. For the other elements, the cut-off values chosen represent a percentage of the showing thresholds:

30% of the showing threshold: Ag, Be, Bi, Cd, Co, Cs, Ga, In, Li, Mn, Mo, Nb, Pb, Pd, Pt, Sb, Sn, Ta, Te, Y, Zn and Zr;
50% of the showing threshold: Th, V and W;
75% of the showing threshold: Sc, Ti and U.

Significant Value Thresholds

This threshold corresponds to a content that is statistically different from the entire geochemical database as of June 2017, but does not exceed the anomalous value threshold. A value corresponding to one standard deviation of the normal distribution, i.e., the 84th percentile, was calculated. The rounded results are considered appropriate for all elements, with the exception of beryllium, for which a cut-off content equivalent to 10 times the detection limit was preferred, and uranium, for which a cut-off at 10% of the anomalous threshold was considered more appropriate.