Image Credit: Maria Bulkka/Shutterstock.com
In October 2019, Sienna performed a two-hole drill program at the Slättberg project located in southern Sweden. The target of that program was two electromagnetic (EM) anomalies identified by downhole surveys conducted at the end of the 2018 drill program.
One anomaly was identified in and around the SIE-18-006 drill hole, which is situated at the west end of the trend of historic nickel mines. The other anomaly was identified close to the SIE-18-003 drill hole, in the vicinity of the center of the mineralization trend.
The SIE-19-002 drill hole was drilled to investigate a powerful EM response to the west of the SIE-18-003 drill hole at the center of the mineralization trend. The SIE-19-002 drill hole intersected a PGE-rich vein with a width of 0.55 m (from 88.0 m to 88.55 m), averaging 1.79% Cu, 0.22% Ni, and 4.15 ppm (4.15 g/t) PGE (4.05 g/t Pt versus 0.095 g/t Pd).
In this vein, there is a prominent peculiar enrichment of PGE, which represents one of the maximum values ever reported from the property. PGE contents observed in the 2019 drill holes of Sienna show powerful PGE potential on the project.
In the SIE-19-002 drill hole, unmapped mine workings were intercepted at a depth of 70 m. This shows that nickel mineralization was extensively mined than suggested by historic records.
The SIE-19-001 drill hole was drilled to investigate the western anomaly. Multiple sulfide mineralization zones were intercepted in this hole over an interval of 28 m at depths of 167 to 195 m. This represents the widest sulfide mineralization zone ever intercepted on the property.
Sulfide mineralization was found as huge sulfide veins and in breccias. It is also associated with an extremely thick swarm of mafic dikes. The highest intercept from within the sulfide mineralization zone was 5.0 m (from 167.75 to 172.75 m), averaging 0.06% Co, 0.47% Cu, 0.57% Ni, and 0.48 ppm PGE (actual thickness predicted to be 55%–65% of reported interval), or about 1% Ni equivalent.
Textures in the sulfide intervals indicate tectonic sulfide remobilization from an adjacent source. Several thick mafic dikes were also found in SIE-19-001. These dikes were not observed in surface exposures or in the shallow drill holes in other parts of this area.
The higher PGE values, sulfide abundance, and multiple mafic dikes indicate that Sienna is turning out to be a source area for the sulfide mineralization and related mafic intrusions, with drilling performed to increasingly deeper levels in the western target area.