Title

Investigation of Federal Mining Claim Summary Statistic Data


Author

Lara Pucik Christensen
American River College
Geography 350: Data Acquisition in GIS; Fall 2005
Contact Information: lara@lanset.com


Abstract

This paper reviews the most recent mining claim data extraction process developed and implemented by the U.S. Geoglogical Survey to summarize mining claim statistics maintained by the Bureau of Land Management and to integrate them with spatial data collections. Use of the datasets was demonstrated through analysis of mining claim activity and status on a geographic basis: specifically, the number and location of mill site claims by status (active or closed as of the end of 2003) in California were determined. For the time period 1976-2003, a total of 1647.98 active mill site claim equivalents were found to be contained by 256 PLS land sections, and a total of 8696.97 closed mill site claim equivalents were found to be contained by 1254 PLS land sections.


Introduction

Since 1866, when Congress enacted regulations formalizing requirements for establishing mineral rights on Federal Land, mining claims in the United States have been recorded by various federal agencies. Demand for accessible and timely information regarding mining claim activity has led to the development of processes to extract and summarize mining claim statistics on a regular basis. These processes have evolved over the last decade as information system technology has improved and data management methods (as well as the federal agencies responsible for implementing them) have changed.

This paper summarizes the most recent mining claim data extraction process developed and implemented by the U.S. Geoglogical Survey (USGS) to summarize mining claim statistics in the Bureau of Land Management’s (BLM) current Legacy Repost 2000 (LR2000) database and integrate them with compiled spatial data (Causey, 2005) . It also demonstrates how such summary data may be used to analyze mining claim activity and status on a geographic basis: specifically, the number and location of mill site claims by status (active or closed as of the end of 2003) in California was determined.

Such summary statistic data is useful to a variety of sectors, including the mining, geology, public safety, resource management, and environmental fields. In this case, locating recorded mill sites in California could be used as a first step in identifying, investigating and prioritizing sites that may be of mine process value or that may present threats to the environment or public safety.


Background

Use of the BLM mining claim recordation system for examination of exploration activity on Federal Lands was initiated by the U.S. Bureau of Mines (USBM) and continued by the USGS after closure of the USBM in 1995. In 1996, Campbell described a procedure for processing BLM mining claim recordation system data using ESRI ArcInfo and dBASE software. Statistical results for various states were published in 1996 by Campbell and Hyndman and in 1999 by Hyndman and Campbell .

In Campell’s original extraction method, “mine claim density” (count of claims on a given section of land) was calculated after assigning each mining claim to one and only one Public Land Survey (PLS) section of land (the first section record encountered when looping through a dataset in which one claim spanned multiple sections). By arbitrarily assigning a mining claim spanning multiple sections to only one section, this method thus did not always attach a value to all the sections in which there were claims.

Since that time, the BLM has converted their mining claim data to the Legacy Repost 2000 system (LR2000). Causey (2005) developed and implemented new methodology for extracting statistical data from this system. Causey’s method incorporates significant improvements in representing mine claim density by proportioning claims spanning multiple section equally between all spanned sections. Although this method does not apportion mining claims spanning multiple sections based on actual areas, it yields an improved density surrogate that Causey calls a “claim equivalency” value. A given claim equivalency value can represent a variety of scenarios covering varying combinations of whole or fractional claims on a given section. Causey reports that this claim equivalency value provides a better representation of spatial distribution of claims as well as a better measure of intensity of interest within land sections than did the previously developed “mine claim density” factors that did not apportion claims spanning multiple sections. The difference between the two methodologies is graphically depicted in Figure 1.
Apportionment
Figure 1. Improved methodology for apportioning claims spanning multiple sections.


Data

Causey’s 2005 report provides links to two kinds of data: tabular summary statistics (in dBASEIII and ASCII formats) derived from BLM mining claim records using his improved apportionment methodology, and spatial databases of Public Land Surveys in shapefile format compiled from a variety of sources.

Mining claims recorded in the BLM database include lode claims, placer claims, tunnel sites, and mill sites. Mining claim data from the BLM’s LR2000 Oracle database was extracted on January 15, 2004; statistics from this dataset represent mining claims placed on U.S. Federal Lands between 1976 and 2003. Aggregate statistics for this time period derived (with apportionment as described earlier) and provided by Causey in individual dBASEIII or ASCII files include:

• number of all claims in each section by year,

• number of lode claims in each section by year,

• number of placer claims in each section by year, and

• total number of claims by type and status (active or closed) at the end of 2003.

Public spatial databases collected by Causey and provided as shapefiles include PLS section polygons to which a user can attach data from the summary statistics as well as FGDC-compliant metadata. Land sections were uniquely identified using a standardized composite code based on the meridian, township, range and section (MTRS) of the section.

Use of the standardized MTRS key to link spatial and tabular data is shown for sample California data in Figure 2.

Sample Data
Figure 2. Use of standardized MTRS key to link spatial and tabular data.


Methods

In order to identify the number and location of active and closed mill sites in California for this project, the following California mining claim summary statistic and PLS spatial datasets were downloaded from the USGS website (http://pubs.usgs.gov/ds/124/California/):

• ca_total.txt (total number of claims by type and status at the end of 2003)

• ca_pls_03.shp (PLS section polygons for which claims were filed 1976 - 2003)

The ca_pls_03 shapefile (in Geographic coordinates, NAD 27) was uploaded into ArcMap 9. This file contained 21,883 records, each of which was a PLS polygon with a unique identification code (MTRS attribute). The ca_total.txt file was then added. This table contained 35,480 records, each of which represented a claim equivalency statistic for a given type and status of claim filed between 1976 -2003 in California. Each claim statistic contained the following attributes:

• MTRS identification code (meridian, township, range, section (MTRS) code for the PLS section polygon to which the statistic applies)

• case_disp (status of the claim: active or closed)

• case_type_txt (type of claim: lode, placer, tunnel, mill)

• claim_equiv (number of claims apportioned to the section)

Initially, the ca_total.txt table was added and joined to the PLS shapefile using MTRS as the common linking attribute. Attempting to extract PLS sections containing millsites from the shapefile using “select by attribute” on a computer with a 2.3 GHz Pentium 4 processor and 1 GB of RAM was unsuccessful, apparently due to the large number of records. The ca_total.txt file was therefore preprocessed in Excel to extract millsite records by status.

The processed data tables containing only millsite records were then added to the map, joined to the PLS section shapefile, and symbolized proportionally based on claim equivalency. Two maps (active and closed claims) showing millsite density per PLS section were created by overlaying the claim data on a stock ESRI basemap of California (1990 U.S. census data) displayed in the NAD83 California Teale Albers projection.


Results

Figures 3 and 5 show the locations and densities of active and closed (as of the end of 2003) millsite claims in California per PLS land section for the time period 1976 – 2003. A total of 1647.98 active millsite claim equivalents are contained by 256 PLS land sections. A total of 8696.97 closed millsite claim equivalents are contained by 1254 PLS land sections. San Berdardino and Inyo counties appear to contain the most millsite claims. Figures 4 and 6 show histograms of the claim equivalency data; maximum closed millsite claim equivalency was 232; maximum active millsite claim equivalency was 93. The majority of claim equivalency values for both active and closed millsites fell in the 0 to 10 range,indicating that while some PLS land sections contain a large number or millsite claims, most contain only a few.

Active Millsites Map

Figure 3. Map of Active Millsite Claim Equivalency in California, 1976-2003.
Active Millsites Histogram

Figure 4. Histogram of Active Millsite Claim Equivalency in California, 1976-2003.
Closed Millsites Map

Figure 5. Map of Closed Millsite Claim Equivalency in California, 1976-2003.
Closed Millsites Histogram

Figure 6. Histogram of Closed Millsite Claim Equivalency in California, 1976-2003.

Conclusions

This project demonstrated the utility of the USGS mining claim summary statistic data set for identifying and locating various types of mining claims in the United States. Because the USGS has processed and summarized data from the BLM database of mining claim records, and provided a collection of spatial data processed to link readily to the summary statistics, visualization and analysis of mining claims is now a relatively straightforward task.

The largest limitation encountered was that of computing power: because the datasets were so large (over 35,000 records), a fairly typical desktop machine (2.3 GHz processessor with 1GB RAM) running ArcMap 9 had difficulty sorting and extracting data within ArcMap. Preprocessing the data in Excel to extract records of interest (and thereby limit file size) was required to allow ArcMap to successfully handle the dataset.

Mining claim activity is a topic of interest in many fields, including geology, mining, environmental engineering, and public land management. The maps examining millsite claim statistics in California created for this project could be used for a variety of purposes such as beginning to prioritize sites for restoration or identifying areas that may still be of mining resource value. Further processing of the maps to quantify spatial distribution of claims by county, for example, could be performed as part of a mine site inventory. As such, these maps demonstrate the value and utility of the summary statistic dataset prepared by the USGS from BLM mining claim records.


References

Causey, J.D., 2005. Mining Claim Activity on Federal Land for the Period 1976 through 2003. U.S. Geological Survey Digital Series report 124, URL= http://pubs.usgs.gov/ds/124.

Campbell, H.W., 1996. Procedure for Making a Mining Claim Density Map from BLM Claim Recordation Digital Data. U.S. Geological Survey Open-File Report 96-736, URL= http://pubs.usgs.gov/of/1996/of96-736.

Campbell, H.W. and P.C. Hyndman, 1996. Digital Mining Claim Density Map for Federal Lands in the Pacific Northwest. U.S. Geological Survey Open-File Report 96-737, URL= http://pubs.usgs.gov/of/1996/of96-737.

Hyndman, P.C., and H.W. Campbell, 1999. Digital Databases Containing Mining Claim Density Information for Arizona, California, Colorado, Idaho, Montana, Nebraska, New Mexico, Nevada, Oregon, South Dakota, Utah, Washington, and Wyoming Created From the BLM Mining Claim Recordation System: 1996. U.S. Geological Survey Open-File Report 99-325, URL= http://pubs.usgs.gov/of/1999/of99-325.