The Minnesota Department of Natural Resources, Lands and Minerals Division, maintains a Drill Core Library in Hibbing, Minnesota. It serves as the State of Minnesota's repository for archiving bedrock and earthen material core samples collected during minerals exploration, engineering, and geoscience research programs across the state. The library attracts a world-wide audience of researchers, mineral explorers, and engineers who reuse existing core samples to develop new ideas about Minnesota's mineral resources and geology.
The three buildings that comprise the drill core library house more than 3 million lineal feet of drilled core samples archived from approximately:
- 7,000 mineral exploration cores,
- 1,500 roadway and bridge foundation cores, and
- 500 cores collected during scientific, governmental, and academic research.
Infographic: 3 Million Feet in Perspective »
The library has space available for viewing the cores and maintains corresponding data files containing location maps, geologic descriptions, geophysical and geochemical information when such information exists. Sampling of drill core is encouraged within set guidelines.
The importance of the library
Viewing Minnesota's subsurface
The importance of these drill core samples cannot be overestimated. Explorers are searching for mineral deposits in the bedrock. These deposits can be difficult, or impossible to assess because most of the bedrock in Minnesota is buried under glacial sediments.
Conceptual graphic illustrating depth to bedrock
Drill core samples, combined with indirect methods such as geophysics and geochemistry, provide the only glimpse of the bedrock for many tens of square miles in Minnesota. These drill core samples attract a worldwide audience of scientists who use core samples to develop new ideas about the capacity of the state's bedrock and glacial materials to host mineral resources and also to model the geologic forces and features that have shaped the state's bedrock. The materials at the library have contributed to the discovery of three valuable nonferrous mineral deposits-The Birch Lake deposit, the Maturi deposit, and the Tamarack deposit.
Infographic: Depth to Bedrock »
Map: Significant nonferrous mineral deposits »
Core sample box for drill hole LL-85-1. Each core box normally is 2 feet long with 5 core segments per box, or 10 feet of core per box. Typical core boxes are designed to hold 50 lbs weight or less.
Limiting the need for additional drilling
Drill core samples are often reused several times in exploration programs, academic research, and engineering projects. This is a very important fact because the library is limiting the need for additional drilling disturbances because it stores and makes available drill core samples. Library visitors appreciate this because the cost of acquiring new core samples is very expensive. It has been estimated that it can cost 100,000 dollars to obtain the total core from 1,000 feet of drilling. This estimate is based on all drilling related costs from the geologist time to the lab analysis. Archived cores in the drill core library have been reused for the advancement and evaluation of several copper-nickel, gold, titanium, and iron deposits and prospects (Tamarack, Birch Lake, Maturi, Spruce Road, Serpentine, Mud Creek, Lost Lake, Virginia Horn, Longnose, TiTac, Buckeye, Emily, and others).
Infographic: General map of core sample drilling locations in Minnesota »
Mapping and Research
The Drill Core Library is used frequently by educational institutions, geologic agencies, and engineers to further the scientific research of Minnesota's geology. The Minnesota Geological Survey (MGS) has used the drill core library to assist in mapping bedrock and surficial geology for their County Geologic Atlas program. Data derived from those maps are used by DNR's Ecological and Water Resources Division to develop hydrogeologic models, such as, depth to aquifers, or pollution sensitivity. Professors and graduate students from around the world visit the library to further their own research interests. Their new research advances our knowledge of Minnesota's geology.
MGS County Geologic Atlas Program »
DNR Waters County Geologic Atlas Regional Assessment Program »
Scheduling your visit
The Drill Core Library is located in the DNR's Hibbing office at:
1525 Third Avenue East Hibbing, MN 55746
While the library is open to the public during normal business hours you must contact the DNR before visiting the facility. The DNR prefers to be notified two weeks in advance of each visit.
Before Your Visit
In order to better assist those visiting the Drill Core Library the DNR has prepared a pre-visit document listing information we would like to know when you contact us.
Pre-visit information document »
Viewing drill core
The drill core library has two heated rooms in which to view your selected drill core samples. The DNR will retrieve your selected core samples in preparation for your visit. Please see the 'Schedule Your Visit' tab above for more information.
Sampling drill core
The DNR encourages sampling of publicly available drill core for chemical analysis, thin sectioning, etc. The following documents are designed to preserve and enhance the value of these unique cores. Please preview or download these documents if you plan to sample drill core. Your cooperation will be greatly appreciated. If you have any questions please contact a staff member.
Sampling guidelines »
Policy and Instructions for Sample Request Form »
Sampling Request Form »
Delivering drill core
Delivering drill core:
In order to better assist those delivering drill core to the Drill Core Library the DNR prefers a minimum 2 week notice in advance of core deliveries and pickups to best ensure meeting the customer's needs. The DNR has prepared a pre-deliver document listing information we would like to know before you deliver drill core.
Delivering core information document »
Policies and Purpose
View a PDF of this information »
The majority of drill samples in the library are public data and available for viewing. Most exploratory boring samples are delivered to the library in fulfillment of statutory requirements which have been in effect since 1980.
- If a state mineral lease terminates, then the drill cores associated with that lease become state property and public data. The drill samples remain public data even if a new lease becomes active on the same mining unit.
- Exploratory Boring Procedures- Minnesota Statutes 103I.601 »
- Submission of Data from Exploratory Borings- Minnesota Statutes 103I.605 »
Those same statutes also identify that some core samples and related data are not public data meaning they are not viewable by the public. This is due to the core sample and data being on an active state minerals lease. The DNR must follow this law. If you wish to view confidential core, then you need to be an employee of the state mineral lessee or have written permission from the state mineral lessee.
The primary purpose of the Drill Core Library is to receive, preserve, and make available drill samples to serve the state policy for mineral development (M.S. 93.001). This means that environmental impacts are reduced when existing drill samples can be re-used multiple times such that the total number of drill holes is reduced. The drill samples have also proven to be extremely valuable for academic researchers, such as university professors and graduate students. Many graduate student theses have been possible largely based upon the free access to drill core samples in this library. Further, the drill samples are available for environmental research, such as to understand the natural background trace element composition of the bedrock materials.
View an interactive map displaying the geographic distribution of core and other samples stored at the drill core library.
The web map also includes these GIS layers:
- DNR's state minerals leases (active and past minerals leasing)
- Footprints of DNR mineral exploration documents (minarchive and Lehmann Collection) with links to view and download the documents
- Footprints of DNR mineral potential projects with links to view and download the digital data files
- DNR's Public land survey boundaries
- DNR's high resolution surface relief (LiDAR)
- Geomorphology of Minnesota
- Soil Surveys from the NRCS-USDA
- The DNR is hosting the following GIS datasets from the Minnesota Geological Survey (MGS): bedrock geology, bedrock outcrops, glacial overburden model (depth to bedrock), aeromagnetic data, and footprints of MGS reports and projects with links to view and download the digital data files (New).
Important policy note
The state policy is that users must share their research results from core sampled.
All future users benefit from the efforts of individuals, researchers, and companies.
Where can I find more information about Minnesota's minerals?
MCC website »
The Minnesota Minerals Coordinating Committee (MCC) is a multi-agency committee responsible for coordinating Mineral Diversification Projects that:
- "Provide for the diversification of the State's mineral economy through long term support of mineral exploration, development, production, and commercialization".
The MCC website has a variety of geologic and mineral related maps, GIS data, and other useful links.
Interested in recent exploration drilling locations
Check out the DNR's private exploration drilling webpage. The webpage is updated annually and displays where private companies have completed exploration drill holes.
Private Exploration Drilling »
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