DGGS Digital Data Series 18, Alaska Minerals Database, is a working, internal database that supports multiple data products developed by the Alaska Division of Geological & Geophysical Surveys (DGGS), including the Alaska Mineral Industry Report series (https://dggs.alaska.gov/pubs/minerals) and a web service of significant mineral industry occurrences and industry activity in 2020. DGGS anticipates developing additional products from the database in the future. This abstract and data dictionary will be updated as more of the database becomes publicly available over time. The full, unpublished database contains information about significant mineral occurrences in Alaska, including industry activity by year, mineral resource estimates, mine production statistics by year, and an interpreted mineral system type using the classification scheme of Hofstra and Kreiner (2020). The database also associates records in Alaska Resource Data File (ARDF; U.S. Geological Survey, 1996) with significant mineral occurrences, as interpreted by DGGS. DGGS annually compiles mineral industry information from past-year statements issued by companies, including press releases and corporate annual and financial reports, as well as phone interviews, replies to questionnaires, and news media articles. Only publicly available data compiled by DGGS are visible; confidential data are incorporated into statewide figures. The database is actively updated as new mineral activity data become available each year. Property information and previous years' data will be updated to resolve errors, reflect new geologic interpretations, and display newly available data. Consequently, products developed from the database may change over time as information and figures are updated. DGGS encourages members of the public to contact DGGS' Mineral Resources Section staff to discuss potential changes to the data or errors to be resolved in our derivative products. The data are available from the DGGS website: http://doi.org/10.14509/30873.

This data contains the location of coal resources within the State of Alaska and created in cooperation with the Alaska Coal Association. Total hypothetical coal resources in Alaska exceed 5.5 trillion short tons, equal to about half the estimated coal resources of the United States. Major coal deposits occur in the Northern Alaska, Nenana, and Cook Inlet-Susitna provinces.

Estimated Alaska coal resources are largely in Cretaceous and Tertiary rocks distributed in three major provinces. Northern Alaska-Slope, Central Alaska-Nenana, and Southern Alaska-Cook Inlet. Cretaceous resources, predominantly bituminous coal and lignite, are in the Northern Alaska-Slope coal province. Most of the Tertiary resources, mainly lignite to subbituminous coal with minor amounts of bituminous and semianthracite coals, are in the other two provinces. The combined measured, indicated, inferred, and hypothetical coal resources in the three areas are estimated to be 5,526 billion short tons (5,012 billion metric tons), which constitutes about 87 percent of Alaska's coal and surpasses the total coal resources of the conterminous United States by 40 percent. Coal mining has been intermittent in the Central Alaskan-Nenana and Southern Alaska-Cook Inlet coal provinces, with only a small fraction of the identified coal resource having been produced from some dozen underground and strip mines in these two provinces. Alaskan coal resources have a lower sulfur content (averaging 0.3 percent) than most coals in the conterminous United States are within or below the minimum sulfur value mandated by the 1990 Clean Air Act amendments. The identified resources are near existing and planned infrastructure to promote development, transportation, and marketing of this low-sulfur coal. The relatively short distances to countries in the west Pacific Rim make them more exportable to these countries than to the lower 48 States of the United States. Another untapped but potential resource of large magnitude is coalbed methane, which has been estimated to total 1,000 trillion cubic feet (28 trillion cubic meters) by T.N. Smith 1995, Coalbed methane potential for Alaska and drilling results for the upper Cook Inlet Basin: Intergas, May 15 - 19, 1995, Tuscaloosa, University of Alabama, p. 1 - 21.

Estimated Alaska coal resources are largely in Cretaceous and Tertiary rocks distributed in three major provinces. Northern Alaska-Slope, Central Alaska-Nenana, and Southern Alaska-Cook Inlet. Cretaceous resources, predominantly bituminous coal and lignite, are in the Northern Alaska-Slope coal province. Most of the Tertiary resources, mainly lignite to subbituminous coal with minor amounts of bituminous and semianthracite coals, are in the other two provinces. The combined measured, indicated, inferred, and hypothetical coal resources in the three areas are estimated to be 5,526 billion short tons (5,012 billion metric tons), which constitutes about 87 percent of Alaska's coal and surpasses the total coal resources of the conterminous United States by 40 percent. Coal mining has been intermittent in the Central Alaskan-Nenana and Southern Alaska-Cook Inlet coal provinces, with only a small fraction of the identified coal resource having been produced from some dozen underground and strip mines in these two provinces. Alaskan coal resources have a lower sulfur content (averaging 0.3 percent) than most coals in the conterminous United States are within or below the minimum sulfur value mandated by the 1990 Clean Air Act amendments. The identified resources are near existing and planned infrastructure to promote development, transportation, and marketing of this low-sulfur coal. The relatively short distances to countries in the west Pacific Rim make them more exportable to these countries than to the lower 48 States of the United States. Another untapped but potential resource of large magnitude is coalbed methane, which has been estimated to total 1,000 trillion cubic feet (28 trillion cubic meters) by T.N. Smith 1995, Coalbed methane potential for Alaska and drilling results for the upper Cook Inlet Basin: Intergas, May 15 - 19, 1995, Tuscaloosa, University of Alabama, p. 1 - 21.

This data release is part of a 2016-2019 study on the geology, geochemistry and geochronology of ore systems in the eastern Yukon-Tanana Upland region, Alaska. Whole rock chemistry was conducted on 185 samples, mostly from Au prospects, with lesser samples from porphyry Cu prospects. Geographically, most samples are from gold prospects near the Pogo Au mine and east to Black Mountain in the Big Delta quadrangle. Fewer samples are from prospects in the Eagle and Tanacross Quadrangles. Samples were submitted to the USGS contract laboratory and analyzed for select trace elements and gold. Sixty elements were determined by inductively coupled plasma-optical emission spectroscopy-mass spectroscopy (ICP-OES-MS), sodium peroxide fusion (ICP-60). Gold was determined by lead fusion fire assay.

This data release is part of a 2016-2019 study on the geology, geochemistry and geochronology of ore systems in the eastern Yukon-Tanana Upland region, Alaska. Whole rock chemistry was conducted on 185 samples, mostly from Au prospects, with lesser samples from porphyry Cu prospects. Geographically, most samples are from gold prospects near the Pogo Au mine and east to Black Mountain in the Big Delta quadrangle. Fewer samples are from prospects in the Eagle and Tanacross Quadrangles. Samples were submitted to the USGS contract laboratory and analyzed for select trace elements and gold. Sixty elements were determined by inductively coupled plasma-optical emission spectroscopy-mass spectroscopy (ICP-OES-MS), sodium peroxide fusion (ICP-60). Gold was determined by lead fusion fire assay.

Samples from the Alaska Placer Concentrate Collection (APCC) were retrieved from the USGS National Geochemical Sample Archives and submitted for mineralogical analysis at the Colorado School of Mines. The APPC contains samples from placer mining operations throughout Alaska. The original collection contained approximately 5,000 samples that were collected by U.S. Geological Survey geologists between 1895 and 1953 from various mining districts in Alaska (Cathrall, 1993). Much of the collection was lost and surviving samples are housed in the USGS National Geochemical Sample Archive (Cathrall, 1993). Maps showing the sample location and notebooks containing information about the samples in the APCC were retrieved from a Technical Data archive located in the Alaska Science Center in Anchorage. Site locations were digitized from APCC location maps and site information was obtained from the folders that accompany the location maps. Mineralogical analysis was performed on 68 samples selected from the APCC using automated a scanning-electron-microscope (SEM) based mineralogical automated mineralogy system. These data files contain the results of the mineralogical analysis.

The State of Alaska's Strategic and Critical Minerals (SCM) Assessment project, a State-funded Capital Improvement Project (CIP), is designed to evaluate Alaska's statewide potential for strategic and critical mineral resources. The SCM Assessment project is being implemented by the Alaska Division of Geological & Geophysical Surveys (DGGS), and involves obtaining new airborne-geophysical, geological, and geochemical data. For the geochemical part of the SCM Assessment project, thousands of geochemical-sample analyses and locations from historical U.S. Bureau of Mines (USBM), U.S. Geological Survey (USGS), Bureau of Land Management (BLM), DGGS, Alaska Territorial Department of Mines, Alaska Division of Mines and Minerals, and Bureau of Indian Affairs (BIA) reports are being compiled into digital format by DGGS. The objective is to update the State of Alaska's statewide digital geochemical database in order to more clearly identify areas with SCM potential. For this report, DGGS digitally compiled sample and analyses documentation, geochemical assays, and location information for more than 4,400 historical samples that were were originally collected to investigate occurrences of strategic and critical elements throughout Alaska.

The State of Alaska's Strategic and Critical Minerals (SCM) Assessment project, a State-funded Capital Improvement Project (CIP), is designed to evaluate Alaska's statewide potential for strategic and critical mineral resources. The SCM Assessment project is being implemented by the Alaska Division of Geological & Geophysical Surveys (DGGS), and involves obtaining new airborne-geophysical, geological, and geochemical data. For the geochemical part of the SCM Assessment project, thousands of geochemical-sample analyses and locations from historical U.S. Bureau of Mines (USBM), U.S. Geological Survey (USGS), Bureau of Land Management (BLM), DGGS, Alaska Territorial Department of Mines, Alaska Division of Mines and Minerals, and Bureau of Indian Affairs (BIA) reports are being compiled into digital format by DGGS. The objective is to update the State of Alaska's statewide digital geochemical database in order to more clearly identify areas with SCM potential. For this report, DGGS digitally compiled sample and analyses documentation, geochemical assays, and location information for more than 22,500 historical samples that were originally collected to investigate occurrences of strategic and critical elements throughout Alaska.

This report describes the results of geologic mapping and sample analysis from the Richardson district, east-central Alaska.