DNR Open-File Project 392: Regional Survey of Gold in Till, Cook Area, St. Louis County

Map of Sample Locations (click for detailed PDF )

About this project

The DNR is conducting a regional survey of gold in till in the Cook Area of St. Louis County. In this region, an Archean granite-greenstone terrane is overlain by relatively thin layers of Rainy Lobe till and other glacially-derived sediments. In comparable portions of the Archean Superior Province, the quantity and  morphology of gold grains within samples of glacial till has led to the identification of associated bedrock gold deposits.

The results of this survey will support land management decisions in the region of high mineral potential, and may provide useful guidance for private mineral exploration companies that are considering gold exploration programs on State lands.

Project Manager: Don Elsenheimer

Data released on February 4, 2013

January 24, 2013 laboratory reports from Overburden Drilling Management, Ltd Batch 1  -  Batch 2 -  Batch 3 

These laboratory reports from Overburden Drilling Management, Ltd, (ODM) document total gold grain counts and magnetic/non-magnetic heavy mineral concentrate weights in 105 Rainy Lobe till samples that overlie an Archean greenstone belt in the Cook Area of Northern St. Louis County, Minnesota. These orientation survey samples were collected on State-owned or State-administered mineral rights by Mn DNR in September and October, 2012. The approximately 200 square mile Cook Area is an area of historical gold exploration, located in between areas of active gold exploration to the Northeast (Vermilion District) and West (Linden Grove Area). The Mn DNR has a contract with ODM to process the till samples that it collects.

January 24, 2013 ODM data table for 105 CATS series samples 

This MS-Excel electronic spreadsheet converted to PDF, provided to MnDNR by ODM, compiles the results presented in the three separate laboratory reports into a single file.

Data table for 105 CATS series samples with locations and normalized gold grain counts

This data table provides locations as UTM coordinates and normalized gold grain counts (10kg sample weight) for the 105 samples identified in the ODM report. Five relatively small (<5 square miles) clusters of anomalously high gold grain counts were identified. Three of these five clusters are located in areas of the Archean granite-greenstone terrane that have not been previously explored for gold mineralization.

Map of Cook Area sample locations and gold grain counts

This map displays sample locations, normalized total gold grain counts and areas historically offered by the State of Minnesota for mineral exploration, overlain on a 2010 aerial photograph of the Cook Area. The State of Minnesota has a dominant land position within this accessible greenstone terrane.

Next data release: ArcGIS File Geodatabase

ArcGIS data files will be released separately that incorporate the data into a geodatabase alongside associated mineral exploration and mineral rights ownership information. The Cook Area gold-in-till data will also be integrated into a separate ArcGIS compilation of MnDNR till sample data collected in Northern Minnesota from 2005-2013.

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