Drill Core Library

Some areas of the Drill Core Library remain temporarily closed as we address on-going safety concerns. During this process, the public will be able to request selected core, access viewing rooms, and make deliveries. Please email [email protected] for more information, or call 218-231-8445.

Overview

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 linear 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 »