Project of the Week: FireFox Gold



FireFox Gold Corporation (TSX.V: FFOX), with its flagship projects, Jeesiö and Mustajärvi, is continuing exploration and evaluation of claims in the Central Lapland Greenstone Belt (CLGB) in Finland. Both of these projects are focused on the delineation of structurally-controlled orogenic gold, starting from geophysical surveys and continuing to DC drilling projects. Recent drilling in the Northeast target of the Mustajärvi deposit revealed bonanza-grade gold over a 1.35m interval (93.8 g/t) just below a larger interval of 16.m hosting 7.7 g/t gold - a very promising drill core indeed!

Believe it or not, the results from the established projects are not the most exciting news from FireFox Gold! Beginning in early 2021, geophysical data on the 100% owned Sarvi project kickstarted a summer of sun and surveys for the exploration team at FireFox. The Sarvi project (Fig. 1) butts right up to Rupert Resources’ Ikkari project, which you can find more information on here. Early results are promising for the continuation of gold mineralization from Ikkari to Sarvi, just a couple kilometers north.

The rocks of the Central Lapland Greenstone Belt consist of poorly differentiated mafic volcanic rocks and metasedimentary rocks from the Paleoproterozoic, formed between 1.92-1.79 Ga. At the Sarvi property, these are mapped as tholeiitic basalts, part of a formation which has been identified as a gold potential by the Geological Survey of Finland (Niiranen et al, 2015).

The gold in the CLGB orogenic, and it was produced during collision between ancient oceanic plates and the Fendoscandian shield, which makes up the Finnish crust. Through successive suturing in the Proterozoic, the shield amalgamated different arc terranes and oceanic crustal components during the Svecofennian Orogen. From 1.92 to 1.76 Ga, the collision with the other subcontinents (such as Karelia and Baltica) and terranes resulted in crustal thickening and the metamorphism of previously accreted mafic crust, which became the greenstone belts that mark the Fendoscandian Shield today (Lahtinen et al., 2018). This process of crustal thickening, and metamorphism has been linked to orogenic deposits in Proterozoic crust around the world (Groves et al., 2019).

Genetic model of orogenic gold formation. Crustal thickening allows fluid collection in the lower crust - fluid which drops out all that shiny gold on it’s way upward!
Genetic model of orogenic gold formation. Crustal thickening allows fluid collection in the lower crust - fluid which drops out all that shiny gold on it’s way upward!

In the common subduction-based model, fluids from down-going slabs are cooked off, stripping metals from the oceanic crust and the overlying mantle (Fig. 2). This fluid collects in the lower crust, making it, as you can imagine, extremely over pressured! When it encounters a structure, such as the suture zones and ancient faults in the CLGB, it propagates along upward and fractures into vein zones as it makes its way through the crust. Fortunately for us, it drops out most of its metal content along the way, leaving behind lode gold in veins along with quartz, sulfides, and carbonates. In terms of geochemical zonation, it is common for Au mineralization to occur with As in deeper parts of the veins, with Sb and Hg anomalies found in shallower parts of the same systems (Groves et al., 2003). It will be interesting to keep an eye on new geochemical exploration data from the team at FireFox.

Interestingly, the geology of the Sarvi project matches certain aspects of the Kittilä Mine, operated by Agnico Eagle. Kittilä Mine is the largest primary gold producer in Europe, and it is hosted in the same type of tholeiitic basalts which host Sarvi. While this doesn’t mean anything outright, the geochemical anomalies at Sarvi match those of Kittilä as well, with high Au and As anomalies accompanied by low Te and Bi - a trait which is uncommon among the other projects operated by FireFox Gold. The mafic “greenstone” lithologies which fill the Sarvi property are common hosts for orogenic gold mineralization throughout the CLGB as well.

Prospects and Potential

FireFox Gold recently published a news report highlighting some of the findings from their surface sampling in the Sarvi project area this summer. A large magnetic low (~ 1km wide) along the southern portion of the boundary corresponds to an interpreted thrust fault striking ENE-WSW. In the vicinity of this fault, surface and till samples contain elevated contents of Au and As (up to 500 ppb Au just in the soil!). Key findings among these samples are surface measurements of 1.5 g/t Au and 1.86% Cu. One drill core in the area has found gold mineralization up to 3.6 g/t (~0.5 m interval), and panning in the area found 118 micronuggets in a 10kg heavy-mineral sample. These promising finds have prompted FireFox geologists to highlight new targets around this zone and a series of perpendicular sample transects.

FireFox conducted sampling missions this past summer in order to check mineralization on later D3 structures (blue dashed lines). Looks like a good decision that will help guide future exploration!
FireFox conducted sampling missions this past summer in order to check mineralization on later D3 structures (blue dashed lines). Looks like a good decision that will help guide future exploration!

As they move into the winter drilling season (check out this interview on the impact of winter drilling in Finland), FireFox Gold will target the highlight areas in Figure 3. Drilling projects are already underway as of early October, and will help guide the exploration team for the project design in the first quarter of 2022. For obvious reasons, everyone at FireFox Gold is excited about the new Sarvi project and what it can add to the already impressive Firefox portfolio.

FFOX NR - Aug, 24th, 2021 -

Groves, D.I., Goldfarb, R.J., Robert, F. and Hart, C.J., 2003. Gold deposits in metamorphic belts: overview of current understanding, outstanding problems, future research, and exploration significance. Economic geology98(1), pp.1-29.

Groves, D.I., Santosh, M., Deng, J., Wang, Q., Yang, L. and Zhang, L., 2020. A holistic model for the origin of orogenic gold deposits and its implications for exploration. Mineralium Deposita55(2), pp.275-292.

Lahtinen, R., Huhma, H., Sayab, M., Lauri, L.S. and Hölttä, P., 2018. Age and structural constraints on the tectonic evolution of the Paleoproterozoic Central Lapland Granitoid Complex in the Fennoscandian Shield. Tectonophysics745, pp.305-325.

Niiranen, T., Lahti, I. and Nykänen, V., 2015. The orogenic gold potential of the Central Lapland greenstone belt, northern Fennoscandian Shield. In Mineral deposits of Finland (pp. 733-752). Elsevier.

Aaron Hantsche

View posts by Aaron Hantsche
Aaron Hantsche recently obtained his PhD in Geology from the University of Geneva in Switzerland, where he studied distal Pb-Zn skarn deposits in southern Bulgaria. Magmatic-hydrothermal deposits are his primary focus, with a bent towards geochemical vectoring tools and field geology. In addition to his work as a geologist, Aaron is a director for the science communication platform, Ore Deposits Hub. His passion for mineral deposits and geo-communication led him to join the Spotlight Mining writing team in October 2021.