The Mitzi 1 occurrence is situated 9 kilometres southwest of Rossland, on the eastern slope of Mount Sophia.

Regionally, the Mitzi 1 property is underlain by intermediate to basic volcanics of the Jurassic Rossland Group. To the east, pelitic, arenaceous, carbonaceous rocks of the Carboniferous Mount Roberts Formation reportedly outcrop.

Locally, the property is underlain by the Elise Formation of the Lower Jurassic Rossland Group, consisting of andesitic flows, tuff, agglomerate, breccia and black siltstone.

The showing consists of a 3.5-metre-wide zone that strikes 005 degrees and dips 75 degrees east in andesite. Mineralization is disseminated and in stringers with quartz in a shear zone, consisting of galena, sphalerite, pyrite, chalcopyrite and pyrrhotite. Fine-grained, disseminated pyrite occurs on the surface and is pervasive in the wallrock. Silicification extends for 2 to 3 metres beyond both walls of the shear as a hydrothermal alteration halo.

By the 1940s, shafts had been sunk along iron-stained and weakly mineralized shears that strike 330 degrees on the Mountain Trail Crown grant., Circa 1946, apparently 58 tonnes of ore were shipped, producing 239 grams of gold, 1131 grams of silver and 3538 kilograms of copper, with the average ore grade approximately 3.7 grams per tonne gold, 17.4 grams per tonne silver and 0.6 per cent copper (Assessment Report 20479). These statistics could be associated with mineralized shear zones near the margins of a granitic intrusive and limestone contact on the Sunset property, Lot 6563 (MINFILE 082FSW160).

In 1974, Bow River Resources Ltd. completed a geochemical survey on the property, finding coincident northwest-trending anomalies of copper, lead and zinc postulated to reflect buried mineralized vein systems (Assessment Report 5355).

In December 1975, Bow River conducted an induced polarization survey on the property. A chargeability anomaly was found to correlate with geochemical anomalies in lead and zinc (Assessment Report 5776).

In 1983, Sage Resources Ltd. conducted prospecting, geological mapping and a geochemical survey. This work is the first documented Mitzi 1 bedrock occurrence. A chip sample across 3.5 metres assayed 0.17 gram per tonne gold, 27.4 grams per tonne silver, 0.29 per cent copper, 2.84 per cent lead and 1.63 per cent zinc (Assessment Report 11723). In 1987, the company conducted a geochemical survey that found mildly anomalous lead, zinc and copper values (Assessment Report 16253). In 1990, the company conducted geochemical sampling, finding elevated lead and zinc values compared to a 1987 survey (Assessment Report 20479).

In 2006, Major Gold Limited conducted a mineral exploration program on the Portland Project. This included prospecting, grid surveys, soil geochemistry, rock sampling, and magnetometer surveys. Results from the soil grid geochemistry survey and the magnetometer survey showed anomalous gold, silver, copper, arsenic, lead, and zinc patterns correlating to known mineralization on the property.