Nickel in northern Savo

Outokumpu-type deposits occur in Pohjois Savo in the Kaavi region, where both copper ore and nickel-cobalt ore are associated within Outokumpu assemblage. Copper ore was mined from the Luikonlahti deposit during 1958-1983 (around 7 Mt @ 1.0 % Cu, 0.1 % Co, 0.5 % Zn, 0.1 % Ni) and nickel ore has been discovered in the Kokka area (A ore around 1.9 Mt @ 0.35 %, B ore around 0.57 Mt @ 0.57 % Ni). An essential part of the Outokumpu assemblage also includes extensive serpentinite formations with large, low-grade nickel-cobalt deposits.

In June 2022, Suomen Malmitutkimus Oy has filed a reservation notice application, Sivakka-Kokka in the Kaavi area (Fig. 1).

Figure 1. Reservation application Sivakka-Kokka in Kaavi area. Figure produced from the GTK MDaE map service 21.07.2022.

Nickel in eastern Finland

Archaean komatiites occur in eastern Finland, in the Nurmes-Lieksa-Kuhmo region, hosting also nickel deposits like Tainiovaara in Lieksa. Some Ni-rich boulders (glacial erratics) have been found in the past, still without the known bedrock source, pointing out the nickel potential of the area. Another economically interested formation, potential for Ni-Cu-Co and PGEs + Au, is the Kuohatti layered intrusion (located in the SW part of the reservation area in Fig. 1). It was studied with bedrock mapping, lithogeochemistry, geophysics and some drilling by the Geological Survey of Finland during 2000’s and 2010’s.

Suomen Malmitutkimus Oy has made in the area in September 2021 a reservation notification, named Kuohatti-Näätä (Fig. 1).

Figure 1. Reservation application in eastern Finland. Figure produced from the GTK MDaE map service 29.09.2021.

Nickel deposits in southern Juva

Several nickel-bearing mafic-ultramafic intrusions occur in southern Juva and surrounding areas. One small deposit was mined during 1970, the Kitula deposit in Puumala.The bedrock is characterized by a granulite facies metamorphism postdating the mafic magmatism. Metamorphism has changed the primary mineralogy and fabric of the intrusive mafic-ultramafic rocks so that they were not identified until the late 1970s. The largest intrusion bodies, later identified and mapped are around four kilometres in length. The nickel deposits of Enonkoski, gold deposits of Rantasalmi and copper deposits of Virtasalmi are found some 40-60 km north of the southern Juva area (Fig. 1).

The NS trending, around 15 km long Pihlajasalo-Heiskalanmäki belt includes four known deposits/showings and boulder indications of additional deposits. The most potential deposits within the belt so far are Pihlajasalo and Heiskalanmäki. From all the deposits, located so far in the southern Juva area the most important one is the Niinimäki deposit, east of the Pihlajasalo-Heiskalanmäki belt (Fig. 2).

Suomen Malmitutkimus Oy completed during 2020-2021 data compilation, new interpretations and a 3D model of the Niinimäki deposit (more at the news site).

More data: Niinimäki, Pihlajasalo, Heiskalanmäki.

Nickel deposits
Figure 1. Nickel deposits (green squares) on the metamorphic map of southern Savo. Also shown gold (yellow), copper (purple) and zinc deposits (blue). Nickel targets of Suomen Malmitutkimus Oy outlined by the red rim. Figure produced from the GTK MDaE map service.
Figure 2. Nickel deposits (green squares) in the Pihlajasalo-Heiskalanmäki belt and the Niinimäki nickel deposit. Mafic-(ultramafic) intrusions by black. Borders of the reservation application by red dashed line. Bedrock map as background. Figure produced from the GTK MDaE map service 14.04.2020.