DNR Open-File Project 392: Regional Survey of Gold in Till, Cook Area, St. Louis County
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 July 2, 2013
This Certificate of Analysis and Laboratory Report provides analytical and quality control results from the multi-element neutron activation analysis (NAA) of the heavy mineral concentrate (HMC) from 105 samples and 4 duplicate samples of glacial till from the Cook Area. The HMC samples were previously processed by Overburden Drilling Management, Ltd. (see February 4, 2013 data release below).
This MS-Excel spreadsheet, created by ActLabs and converted to PDF, provides the analytical and quality control results from NAA analysis of 105 samples and 4 duplicate samples of HMC in a data table format. Non-detect values are reported as text strings (e.g. “< 5”).
This MS-Excel spreadsheet adds sample locations as UTM coordinates to the NAA results for the 105 HMC samples. Information provided in the ActLabs data table on analyte detection limits, units of measure, and analytical methods was stripped from this data table in order to create a format suitable for import into Arc-GIS. The “less than” non-detect values reported in the ActLabs data table are replaced by values that are one-half the method detection limit. The original ActLabs data table and QC results are archived in this file as separate sheets.
Data released on February 4, 2013
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.
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.
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.
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.
For more information:
Project Leader - Don Elsenheimer, Ph.D
500 Lafayette Road
St. Paul, Minnesota 55155-4045
Disclaimer and Copyright Protection: Maps, Reports, Data, and Other Information - The State of Minnesota makes no representations or warranties express or implied, with respect to the use of the information contained herein regardless of its format or the means of its transmission. There is no guarantee or representation to the user as to the accuracy, currency, suitability, completeness, usefulness, or reliability of this information for any purpose. The user accepts the information “as is." The State of Minnesota assumes no responsibility for loss or damage incurred as a result of any user’s reliance on this information. All maps, reports, data, and other information contained herein are protected by copyright. Permission is granted to copy and use the materials herein for any lawful noncommercial purpose. Any user of this information agrees not to transmit or provide access to all or any part of this information to another party unless the user shall include with the information a copy of this disclaimer.