Saint-Elie Mine

 

Localisation

Saint-Élie mine is located in the central north of the French Guiana around thirty kilometers west of Petit Saut Lake. Three hours are necessary to arrive on the mine using road en boat. By air, it's possible to come in thirty minutes.

 

 

Saint-Élie concession history

Soon after the gold discovery on the Saint-Elie region in 1873, the different placer deposits were mined intensively by different methods: washing, crushing, open-pit mining and underground galleries. Primary and secondary minerals will cease to be mined at the beginning of the 1950s. The production of 18 tons of gold in total over this first period is followed by a long latency period which lasted until 1975.

In the mid-1970s BRGM starts its work of mining inventory for the entire French Guiana department. It focusses in particular on evaluating the Saint-Elie river’s tailings in 1985.

These studies provide a renewed interest and mining activities starts again with Gerard Ostorero in 1992. The Esperance Mining Company focused on artisanal mining of the river bed. Then GUYANOR Resources S.A. becomes owner of the property in 1993 and begins reconnaissance and exploration works by creating the Mining Society of Saint-Elie. The lease is then sold 3 years after. Guyanor will put an end to exploration in 1998. In 2002, after four years of mining exploitation by private convention, CME buys SMSE.

 

Saint-Elie mine localisation

 

Choubert's picture

Geological context

The Saint-Elie concession and the exclusive research permit of Pédral are located in the northern part of the Guiana Shield. These mining properties cover three groups of paleoproterozoic terrains: (1) a NW-SE segment of the northern French Guiana greenstone belt (Paramaca sequence), (2) TTG granitoid series of the French Guiana Central Complex (tonalite-trondhjemite-granodiorite magmatism), (3) metamorphic sediments which belong to the Superior Detrital Ensemble (Bonidoro sequence).

 From center to southeast of the Saint-Elie concession, greenstone belt terrains are composed by mafic to felsic volcanic rocks (rhyo-dacite, andesite, basalt ...) metamorphosed under greens-schist to amphibolite facies. These meta-volcanic terrains are cross-cut and framed by intrusions of the French Guiana Central Complex.

 Plutonic rocks of the French Guiana Central Complex are represented, by biotitic granite outcropping widely in south and west of the Saint-Elie concession, and by a quartzitic diorite intrusion covering the southern part of the Pédral permit.

The Superior Detrital Ensemble covers north-east of the Saint-Elie concession and whole center and north of the Pédral permit. It corresponds to a thick sequence of mica-schist including quartzitic and micro-conglomeratic sandstone bars. The contact between these basin meta-sediments and greenstone belt rocks or TTG granitoids corresponds to a major shear zone showing numerous gold mineralizations.

 

 

 

Geological map

 Important sectors

Three sectors stand out for their gold mineralization potential: (1) southeast Saint-Elie concession, (2) Pédral sector, (3) Republique-Louise sector.

The southeast of the Saint-Elie concession is subject to mining for over a century. Gold deposits are located in greenstone belt meta-volcanic rocks or within edges of biotitic granite intrusions. They are closely in relation with shear zones that often borrowing NW-SE felsic terrain bands (Michel and Chemin De Fer deposits) or reworking a swarm of WNW-ESE ultramafic lamprophyre dykes (Dévis and Sable deposits). Mineralization is associated with numerous stockworks of quartz veins and veinlets surrounded by disseminated sulphides. Native gold occur within millimetric to decimetric oxidized pyrite crystals.

 

Gold mineralization of Pédral sector has been illegally exploited for more than 5 years before the SMSE obtains the exclusive research permit in January 2016. Mapping these surficial illegal works has revealed numerous occurrences over 6 km, along a NW-SE deep and large shear zone, at the border of Superior Detrital Ensemble basin. Mineralization arises in kaolinitic tectono-hydrothermal lenses that cross-cut undeformed quartzitic diorite near the border of meta-sedimentary basin. Fine native gold occurs in disseminated oxidized pyrites hosted in kaolinitic bands or within thick quartz veins.

 

The Republique-Louise sector has been subject of alluvial and small open-pit mining. Primary mineralization is hosted by greenstone belt meta-volcanic rocks and by chlorito-schist of Superior Detrital Ensemble basin. This sector which includes several surface geochemical anomalies remains underexplored.

Michel deposit cross-section

 

Dévis deposit cross-section

 

Pédral deposit cross-section

Resouces estimation

The two Saint-Elie deposits have been successively estimated in order to make known of its gold resource. Results are shown in the next table:

  Ore
(tons)
Average grade
Au (g/t)
Production
Au (kg)
Production
Au (oz)
Michel 4 528 290 1.79 8 106  260 602
 COSTELLOE D.  (1999) - Guyanor Ressources S.A. & Golden Star Resources Ltd
Michel Zone, St-Elie project – Mineral Resource Estimation
Tailings
Saint-Elieriver
1 646 000 0.70 1 152 37 044
 BOUDRIE M. (2000) - SMSE Rapport Interne
Summary note on the potential of the Saint-Elie Tailings
Devis 6 363 639 2.11 13 427 431 697
LILLIE F.M., ANGOT B., FOURNIER D.A.  (1998) - ASARCO GUYANE FRANCAISE SARL
Devis area (Saint-Elie project) resource
Tailings
D1D2
1 084 050 0.70 759 24 480
CAILLEAU A., LEMOUCHOUX B. (2011) - SMSE Rapport Interne
Tailings D1-D2 / Ressource