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Gretchen Hoffman

 Gretchen Hoffman
Emerita - Principal Sr. Coal Geologist
New Mexico Bureau of Geology & Mineral Resources
New Mexico Institute of Mining & Technology

Gretchen has worked at the New Mexico Bureau of Mines for 34 years as a coal geologist. During this time, she has done field mapping in west-central New Mexico, ran a drilling program for a 3-year coal quality evaluation study in the San Juan Basin, and done numerous coal resource evaluation studies primarily in the San Juan Basin. Developing coal databases has been a integral part of her work at the Bureau. For the past 28 years Gretchen has worked on US Geological Survey cooperative grants evaluating and entering data into the National Coal Resource Data System. From 1998 to 2005, Gretchen was the principal investigator for four Coal Availability studies, funded by the US Geological Survey, evaluating coal resources using GIS. Three of the availability studies were on areas within the San Juan Basin, and the final study (2005) was centered in the Raton basin. Prior to this availability study, Gretchen worked on a project with other researchers at NM Tech looking at the coalbed methane potential in the Raton basin.

Other interests include looking at industrial minerals associated with coal, such as humates, clinker and fly ash. Gretchen's interest in fly ash has led to other research on use of natural and artificial pozzolans and supplementary cementitious materials in cement and concrete. Gretchen has also collaborated with Maureen Wilks on the Mine Map initiative, particularly in collecting historic coal mine maps. As part of this initiative mine maps in the San Juan basin have been geo-referenced and linked to an Arcmap project with associated mine locations with geologic and production data (Open-file report 549).

As part of the Bureau's outreach program, Gretchen has written articles on coal geology and mining for Lite Geology and has taught topographic map reading to teachers at several Rockin' Around New Mexico workshops.


    • Adams State College, Alamosa, CO 1972-1976 - B.A. -- One of the coldest places in the US, known as the Land of the Cool Sunshine. ASU is a terrific small college. I took geology as a science credit at ASC and ended up majoring in geology and archeology.
    • University of Arizona, Tucson, AZ 1976-1979 - M.S.--One of the hottest places in the US--The U of A was a real culture shock for me coming from Adams State, a school of about 2000 students, to a campus of over 60,000 students. I was lucky enough to get an assistantship, have a great thesis committee and an interesting thesis area looking at an early Cretaceous rudist patch reef near Bisbee, AZ.
      Thesis: "Paleoenvironmental Study of a Patch Reef in Upper Mural Limestone in southwestern Arizona, Lower Cretaceous (early Albian) time." Thesis directed by Dr. Karl Flessa, Univ. of Arizona.

    Professional Experience

    May 1980 - present: New Mexico Bureau of Geology and Mineral Resources
    Senior Coal Geologist- June 1992
    Senior Coal Geologist and Database Coordinator- September 2000
    Principle duties include evaluating coal resources in New Mexico and related industrial mineral resources (i.e. humate, clinker, coal combustion byproducts). Resource evaluation includes collecting and interpreting geophysical and quality data, tracking mine production data, and developing digital databases for these data. Monitoring the economics and market trends of the coal industry and related industries is also important in evaluating the economic potential of the resource. Occasionally sampling and mapping of coal-bearing units is required. Dissemination of data and results of evaluations to the public through publications, presentations and service work are an integral part of the job. U.S. Geological Survey cooperative grants have been maintained since 1980 to enter, update, and refine coal data in the National Coal Resource Data System. As part of this contract (NCRDS) coal outcrops are being digitized via arc in geodatabase models for much of the southern San Juan Basin.

    From 1983-1988 involved in a coal quality project to evaluate New Mexico coals through an extensive drilling and analytical program funded in part by the New Mexico Research and Development Institute. Responsibilities included 1) logistics of obtaining access for drilling, 2) bidding process for drilling and logging, 3) overseeing the drilling operation, and 4) analyzing cuttings, geophysical logs and determining core intervals at drill sites. Major reports were produced at the end of each drilling season. A comprehensive report was published (NMBG &MR Bull 141) in 1993 on the results of this study.

    For several years (1996-2005) conducting resource availability evaluations using previously collected data were a major part of the job. These evaluations were funded by the USGS and used GIS to calculate resources for small areas (4 quadrangles and the surrounding 12 quadrangles) and for each coal zone defined by correlation. Areas were chosen based on their potential of becoming economic in the near future. All four studies are available as open-file reports at the NMBG&MR.

    As an offshoot of my coal research I have written articles and given talks on humate, clinker, and fly ash. From 2003-2005 I participated in the development of the Industrial Rocks and Minerals 7th edition, published by the Society for Mining, Metallurgy and Exploration. I authored and co-authored 3 papers; Soil Amendments, Pozzolanic and Supplementary Cementitious Materials, and Abrasives. For this publication I developed and managed the database to track editor and author contact information and deadlines for the senior editors for 114 chapters.

    Duties have been expanded since 2008 to georeference old coal mine maps stored at the Bureau and verify the existing inactive coal mine database for projects funded by OSM resulting in ArcMap and database products (i.e. Gallup coal mines – NMBGMR Open-file report 530, San Juan Basin – Open-file report 549).

    Starting in 2010, took over management of the Perlite testing lab at the NMBGMR (it was decommissioned in 2022). This laboratory received samples primarily from perlite companies throughout the U.S. to test perlite for expansion properties, brightness, density, and sieve analyses. This was one of the few labs in the country doing these analyses that was not operated by a company producing perlite.

    Assist with development and maintenance of databases within the NMBGMR for business office, and hydrology database as well as maintaining several coal databases and a reference library. Starting in 2011 working with NMBG webmaster and geologists to develop geodatabase with back-end forms for data entry a variety of well data from petroleum and geothermal sources. For approximately 8 months migrated geothermal and scout card data into this geodatabase format and develop queries to extract data to meet needs of geothermal contract. Presently there are over 427,000 wells in this database.

    July 1978-1979: University of Arizona (Nuclear Engineering Dept)

    Research Assistant - Assessing the possible use of natural caverns for low-level waste disposal. This entailed describing the formation of limestone caverns and lava tubes, relying on geologic knowledge of rock material, their weathering properties, and effects of groundwater. Individual caverns in several areas of the U.S. were investigated as possible disposal sites. This information was published in two reports (September 1978, and January 1979) from the Engineering Experiment Station, University of Arizona.

    Academic Year 1977-1978: University of Arizona (Dept. of Geosciences)

    Teaching Assistant - Teaching physical geology labs first semester. Reorganizing the invertebrate paleontology collection, second semester.

    Summer 1977: U.S. Geological Survey, Geologic Division, Branch of Exploration Research.

    Geologic Field Assistant - Prepare samples for spectrographic and chemical analysis and conduct arsenic tests. Knowledge and recognition of minerals, such as those containing iron or copper, and their relative abundance in a sample helped to prevent the contamination of other samples, giving accurate spectrographic and chemical results.

    Academic Year 1976-1977: University of Arizona (Dept. of Geosciences)

    Teaching Assistant - Teaching physical geology labs.

    Areas of Interest

    • Coal quality and coal resources of New Mexico
    • Compiling historical data and maps for abandoned coal mines in the State
    • Application of databases and GIS to resource evaluations.

    Professional Societies

    Professional Activities

    • Registration Chairman for New Mexico Geological Society's (NMGS) Spring Meeting, April 1986. General Co?Chairman for NMGS Spring Meeting, April 1987.
    • Co-organizer for coal field trip and compiling guidebook for the Geological Society of America's annual convention (Phoenix, Arizona, October, 1987) with E.C. Beaumont, F.E. Kottlowski, and O.J. Anderson.
    • New Mexico Geological Society Executive Committee-Secretary, 1995, Treasurer, 1996, Vice President, 1997, President, 1998, Past President, 1999.
    • Co-leader for Rocky Mountain section AAPG field trip to Chevron's Mt. Taylor uranium mine and Santa Fe Coal Corp's Lee Ranch coal mine with V.T. McLemore and W.L. Chenowith, October, 1989.
    • Chair for Economic Geology, Geochemistry and Coal session, NMGS Spring Meeting, April 1990.
    • Nominating Committee member, Geological Society of America Coal Division 1991, 1992.
    • Education Committee Chairman, AAPG Energy and Minerals Division, 1991-1994.
    • Co-leader with E.C. Beaumont of pre-meeting field trip for New Mexico Geological Society's 1992 Fall Field Conference. Trip was on coal geology of southeastern San Juan Basin.
    • EMD Short Course Chairman, 1994 AAPG Annual Convention, Denver, CO.
    • Registration Chair, 31st Forum on Industrial Minerals, April 1995, El Paso, Texas.
    • Program Chair, 1996, Chairman, 1997, Board member 1998, Treasurer 2000-2003, NM Central Section of the Society for Mining, Metallurgy, and Exploration.
    • Second Vice Chair 2003, First Vice Chair 2004, Geological Society of America, Coal Division.
    • Co-session chair 2004 Raton Basin: From Coal To Coalbed methane, with Chris Carroll, Colorado Geological Survey, Annual GSA Meeting, Denver, Co. November 7-10, 2004.
    • Co-leader for field trip to the Raton basin for Annual GSA meeting in Denver, October 2013 with Chris Carroll, Wyoming Geological Survey: Coal Geology and Mining History of the Raton Mesa Coal Region, Oct. 25-27, 2013.


    • Data entry and verification of coal data into the US Geological Survey’s National Coal Resource Data System
    • Assist with the development and transition of well and aquifer mapping databases to a relational database management system that will have Web and GIS functionality.
    • Geo-reference and verify data for abandoned coal mines in the for the Raton Basin. This is a continuation of the work done in the San Juan Basin. (Open-file report 549)
    • Manage Bureau’s Perlite testing lab
    • Manage Bureau’s Coal Data Library

    Coal Related Links

    Coal Companies Operating Mines in New Mexico

    There are now (2014) 4 operating coal mines in New Mexico. Two are owned by BHP Billiton and two by Peabody Energy. Recently (December, 30, 2013) the Navajo Mine operated by BHP Billiton was sold to the Navajo Transitional Energy Company, owned by the Navajo Nation.

    Coal and Energy links on the web

    Power Plants in New Mexico