DNR Open-File Project 373: 2008-2010; St. Louis County Vermilion Greenstone Drill Core Assays


The Project 373 area comprises several townships in northern St. Louis County, Minnesota (see location maps in Fig. 1). The Archean rocks are part of the Wawa Subprovince of the Superior Province of the Canadian Shield. Rocks consist of Semi-quantitative2 volcanic-sedimentary sequences and intrusions. Most rocks have been subjected to greenschist facies metamorphism. Outcrop exposure is variable, but good compared with most of Minnesota. Past sampling, maps, and reports have been produced by the Minnesota DNR, the Natural Resource Research Institute, and the Minnesota Geological Surveys.


A “gold rush” in 1865 lead to the discovery of iron ore, but little gold was found. About 100 million tons of direct shipping magnetite and hematite ore within Algoma type Banded Iron Formation(s) (BIF) came from this greenstone. The village of Soudan hosted the first iron mine in Minnesota, with the city of Ely hosting another five major mines. Numerous smaller mines also existed. The iron formation is responsible for one of the strongest magnetic anomalies in Minnesota (Fig. 2). Vermilion underground iron production ceased in Ely in 1965, but several episodes of gold and base metal exploration followed. Exploration activities found numerous gold and base metal showings.

The Project 373 work is meant to complement existing data. 


Drill Core Evaluation of Vermilion Greenstone Belt, Gold Mineralization, Northeast Minnesota.
(61 pages, 8.5 x 11 inches, 6.8 MB)


Project 373, Vermilion Greenstone Gold, New Results from Drill Holes
(60 pages, 8.5 x 11 inches, 8.6 MB)


Data (.zip) files included in the zip file are described below:

  • read_of0710_p373 - Word file with data release organization and limitations
  • p373_openfile_0710_sample_info.xls - Excel file sample descriptive and location information
  • p373_openfile_0710_chemistry.xls - Excel file with ALS Chemex laboratory results
  • p373_openfile_0710_chem_standards.xls - Excel file with DNR submitted standards and accepted values
  • p373_coa_29190_11677484.pdf - PDF file of received chemistry results
  • p373_qcdoc_29190_11677490.pdf - PDF file of ALS Chemex quality control data
  • p373_ddh_list.xls - Excel file with information about drill hole locations
  • RE10060081.csv - CSV file of received chemistry data
  • RE10060081QC.csv - CSV file of received chemistry quality control data

These analyzed samples came from 12 drill holes in greenstone belt rocks that were historically drilled for gold, base-metals, and iron formation. Drill hole samples, and related exploration data, are currently stored at the Minnesota Drill Core Library in Hibbing, Minnesota. The drill holes are located within a large, accessible Archean greenstone terrane within the State of Minnesota between Tower and Ely, Minnesota. Sampling was partially guided by the use of the DNR’s hand-held X-Ray Fluorescence (XRF) analyzer instrument. This new work consists of laboratory analysis of 212 samples by ALS Chemex.

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