Assessment of Undiscovered Deposits of Gold, Silver, Copper, Lead, and Zinc in the United States

A Portable Document (PDF) Recompilation of USGS Open-File Report 96-96 and Circular 1178

By U.S. Geological Survey National Mineral Resource Assessment Team
Recompilation by Paul Schruben

This publication contains the results of a national mineral resource assessment study. The study (1) identifies regional tracts of ground believed to contain most of the nation's undiscovered resources of gold, silver, copper, lead, and zinc in conventional types of deposits; and (2) includes probabilistic estimates of the amounts of these undiscovered resources in most of the tracts. It also contains a table of the significant known deposits in the tracts, and includes descriptions of the mineral deposit models used for the assessment.

The assessment was previously released in two major publications. The conterminous United States assessment was published in 1996 as USGS Open-File Report 96-96. Subsequently, the Alaska assessment was combined with the conterminous assessment in 1998 and released as USGS Circular 1178.

This new recompilation was undertaken for several reasons. First, the graphical browser software used in Circular 1178 was ONLY compatible with the Microsoft Windows operating system. It was incompatible with the Macintosh operating system, Linux, and other types of Unix computers. Second, the browser on Circular 1178 is much less intuitive to operate, requiring most users to follow a tutorial to understand how to navigate the information on the CD. Third, this release corrects several errors and numbering inconsistencies in Circular 1178.

(Click on image to view larger version.)

Viewing Online Files

One way to begin examining the results of the national assessment immediately is to proceed as follows:

1. Install Adobe Reader or check to be certain you already have Acrobat Reader 5 or Adobe Reader 6 installed.
2. Download the 1_NATIONAL_ASSESSMENT.PDF [27.4 MB]. This file must be in the same folder as the index files for Acrobat Search to work.
3. Look for the bookmark named: "Deposit Tract Maps." Click on the triangles (Macintosh) or boxes with plus sign (Windows) to the left of the underlying bookmarks titled: "Alaska" and the "Conterminous U.S." This will display lists of tracts by mineral deposit type for each of these two regions. Some mineral deposit types have multiple tract maps. For example, there are three tract maps for porphyry copper deposits: Porphyry Cu deposits I, II, and III. Each map delineates areas permissive for the occurrence of undiscovered porphyry copper deposits by age. See the Rationale files for descriptions of each tract.
4. Click on a mineral-deposit-type name on one of the lists. This will open a map showing tracts judged to contain undiscovered gold, silver, copper, lead, or zinc in mineral deposits of this type.
5. Each map's key has clickable buttons that will bring up for each tract most of the following data sets:
   1. Cumulative Distribution graph of estimated metal and mineralized rock.
   2. Histogram of estimated metal and mineralized rock.
   3. Table showing the probabilistic estimates of numbers of undiscovered deposits, and the estimated amounts of contained metal and mineralized rock.
   4. Model lists briefly describing this mineral deposit type.
   5. Mineral Deposits list and descriptions of known deposits.
   6. Rationale for selecting the mineral deposit model, delineating tracts, and making numerical estimates of numbers of undiscovered deposits.

Other Files in Open-File Report 02-198

You can download compressed files for the Alaska Assessment [13 MB]
See the readme file for more information.

Alaska_Asssessment\Doc-ReadMe1st.html - User manual for Circular 1178

National Mineral Resource Assessment -- Frequently Asked Questions

Alaska_Asssessment\KNOWNDEP_AK.XLS- Significant Known Deposits of Alaska (Excel)

Alaska_Asssessment\MODELLIST_AK.XLS- Description of Deposit Models (Excel)

Alaska_Asssessment\RATIONALE_AK.DOC- Permissive Tract Text Descriptions and Rationale for Estimates (Word)

Alaska_Asssessment\REFERENCE_AK.DOC- References for the Alaska assessment (Word)

Alaska_Asssessment\TRACTLIST_AK.XLS - Permissive Tracts and Estimated Numbers of Undiscovered Deposits (Excel)

Alaska_Asssessment\TRACTMAPS_AK.PDF- (14.5 MB) Tracts and regions in vector graphics format. (Adobe Acrobat)

Other Links

This publication includes OFR 96-96 and many files modified from those on Circular 1178. The GIS software from Circular 1178 is not included. Both of the original national assessment publications can be downloaded from the following Internet sites:
https://pubs.usgs.gov/openfile/of96-096/
https://pubs.usgs.gov/circular/c1178/

Product Availability

This product (OFR 02-198) is available for sale in CD format from USGS Information Services.

Scientific Contact

For questions, please contact Paul Schruben.