Identification_Information:
  Citation:
    Citation_Information:
      Originator: U.S. Geological Survey

        Cooperating agencies: Bureau of Land Management and U.S. Forest Service 

        Author or compiler: Bradley S. Van Gosen, Richard B. Berg, and Jane M. Hammarstrom

      Publication_Date: 1998

      Title: Map showing areas with potential for talc deposits in the Gravelly, Greenhorn, and
               Ruby Ranges and the Henrys Lake Mountains of southwestern Montana

Series_Information:
        Series_Name: U.S. Geological Survey Open-File Report
        Issue_Identification: OF 98-224-B

      Publication_Information:
        Publication_Place: Denver, Colorado

        Publisher: U.S. Geological Survey

      Online_Linkage: http://greenwood.cr.usgs.gov/pub/open-file-reports/ofr-98-0224-b

Description:
Abstract: For the last several years, Montana has been the leading talc producing state in the
United States.  For example, in 1992 Montana supplied about 40 percent of the U.S. mine
production of talc.  All of this production has come from the large deposits of high purity talc in
the southwestern part of the state.  All Montana talc is currently (1997) extracted from four
mines, each within the study area of this map--the open pit operations of the Treasure State,
Regal, and Yellowstone mines and the underground operation of the Beaverhead mine.  Montana
talc has at least two market advantages: (1) some deposits are very large and near surface,
allowing economic mining by open pit methods; and (2) the deposits are of high purity and lack
tremolite or other amphibole mineral contaminants (such as absestos) that occur in some other
talc-rich deposits.  Talc from southwest Montana is used in ceramics, paint, paper, plastics,
cosmetics, rubber, roofing, flooring, caulking, and agricultural applications.  The talc is also used
in the processes of recycling paper and plastics.
     Exploration and development are likely to continue for the foreseeable future for several
reasons: (1) mines are active in the area at present and an infrastructure for talc processing exists;
(2) large changes in domestic and export talc markets are not expected in the next few years
based on recent market trends; (3) the talc of this region is especially pure and asbestos-free; and
(4) except for potential ground stabilization problems and land disturbance associated with
large-scale open pit mining, no significant environmental impacts are associated with talc mining. 
This map shows areas of surface exposure of Archean-age marble, which is the only rock
type within the study area known to host talc deposits of economic size.  Only exposed marble is
shown because it is most probable that talc bodies will be discovered in this area by recognizing
talc alteration in surface exposures or in the excavations of mines or prospects.  The map also
provides locations and brief descriptions of the talc mines, prospects, and occurrences known
within the map area.  The map was prepared as part of a mineral resource assessment of specified
areas containing federal lands in Beaverhead and Madison Counties of southwestern Montana.
The Bureau of Land Management and U.S. Forest Service chose this area for mineral resource
evaluation to assist their development of land-use managment plans for the region.

Purpose: The Bureau of Land Management and U.S. Forest Service use mineral resource data in
developing land-use management plans for the reasonably foreseeable future.

    Supplemental_Information:
      Map political location: Beaverhead and Madison Counties, Montana
      Compilation scale: 1:250000
      Geology compiled in 1997 and 1998; compilation completed 5/98.  
      Review and revision completed 6/98.
      Paper copy published as Open-File Report 98-224-B 
      Web version (.pdf) released on 12/08/98
      ARC/INFO archive files prepared 12/7/98.

  Time_Period_of_Content:
    Time_Period_Information:  
      Single_Date/Time:
        Calendar_Date: 19981208

    Currentness_Reference: Published in 1998

  Status:
    Progress: Complete.
    Maintenance_and_Update_Frequency: None.
    Mapping is continuing in adjacent areas for different purposes.

Spatial_Domain:
Bounding_Coordinates:
      West_Bounding_Coordinate:-113.0
      East_Bounding_Coordinate:-111.25
      North_Bounding_Coordinate: 45.75
      South_Bounding_Coordinate: 44.5

  Keywords:
    Theme:
      Theme_Keyword_Thesaurus: Geology
      Theme_Keyword: Geologic map
      Theme_Keyword: Talc
      Theme_Keyword: Mineral resource
    Place:
      Place_Keyword_Thesaurus: none
      Place_Keyword: Montana
      Place_Keyword: Gravelly Range
      Place_Keyword: Greenhorn Range
      Place_Keyword: Ruby Range
      Place_Keyword: Henrys Lake Mountains
      Place_Keyword: Beaverhead County, Montana
      Place_Keyword: Madison County, Montana
      Place_Keyword: Beaverhead National Forest, Montana
      Place_Keyword: Dillon
      
  Access_Constraints: none

  Use_Constraints:
    None.  Acknowledgment of the U.S. Geological Survey would be appreciated in products
    derived from these data.  The map data were originally compiled and digitized at a scale of
    1:250,000, and thus the data should be considered accurate only when used at that scale.

Data_Quality_Information:
  Attribute_Accuracy:
    Attribute_Accuracy_Report: Data was entered and checked by the geologist who made the 
    observations.

  Logical_Consistency_Report:

    Map elements were visually checked by the author for overshoots, undershoots, duplicate
    features, and other errors. This digital release is preliminary and has not been thoroughly
    reviewed for conformity with U.S. Geological Survey editorial standards or stratigraphic
    nomenclature.  The paper copy (Open-File Report 98-224-B) was reviewed by one other
    geologist for consistency with basic geologic principles and general conformity to USGS
    mapping standards.

  Completeness_Report:

 This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey
 editorial standards or stratigraphic nomenclature. 
 
 This ARC/INFO release is provided only to be used with the published Open-File Report 
 98-224-B (paper copy).  The topographic base map used for the paper copy release was scanned
 and included as the base for the paper copy; this base is not currently available separately.

  Positional_Accuracy:
    Horizontal_Positional_Accuracy:
      Horizontal_Positional_Accuracy_Report:

        Lines were digitized from original source maps at their original scales and projections, then
        composited at the final scale and projection in GSMAP.

  Lineage:
    Process_Step:
      Process_Description:

        The geologic database was compiled using the GSMAP public domain program (USGS
        Open-File Report 93-511) and later upgraded to the Windows version of GSMAP--
        GSMCAD public domain program (USGS Open-File Report 96-007).  It was exported to
        ARC/INFO using the GSMCAD export function to create ARC/INFO generate files.  The
        ARC/INFO generate files were reloaded into ARC/INFO programs and attributed to match
        the published map (Open-File Report 98-224-B).

      Process_Date: 12/07/98 08:00 AM

Spatial_Data_Organization_Information:
  Direct_Spatial_Reference_Method: Vector

Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Map_Projection:
        Map_Projection_Name: TRANSVERSE MERCATOR
Transverse_Mercator:
          Scale_Factor_at_Central_Meridian: 0.9996
          Longitude_of_Central_Meridian:  -112.0
          Latitude_of_Projection_Origin: 0.0
          False_Easting: 0.0
          False_Northing: 0.0

      Planar_Coordinate_Information:
        Planar_Coordinate_Encoding_Method: coordinate pair
        Coordinate_Representation:
          Abscissa_Resolution: 0.001
          Ordinate_Resolution: 0.001
        Planar_Distance_Units: METERS

    Geodetic_Model:
      Horizontal_Datum_Name: North American Datum of 1927
      Ellipsoid_Name: Clarke 1866
      Semi-major_Axis: 6378206.4
      Denominator_of_Flattening_Ratio: 294.98

Entity_and_Attribute_Information:
  Overview_Description:
    Entity_and_Attribute_Overview:

      The data is supplied in two formats:  
      1. Adobe Acrobat 3.0 .pdf format
      2. UNIX based ARC/INFO format

           DATABASE STRUCTURE - ARC/INFO
====================================

      The database of the map consists of two coverages (root names = TALC and
TALC_P) and three additional auxiliary files:  

     TALC.E00: ARC/INFO interchange file that can be used to create the geology shown on
                        Open-File Report 98-224-B.

     TALC_P.E00: ARC/INFO interchange file that can be used to create point files that display
                            the locations of the 57 talc mines, prospects, and occurrences shown on 
                            Open-File Report 98-224-B.

      Auxiliary files:

     TALC.AML: ARCPLOT commands that create the geologic map of Open-File Report
                            98-224-B from the data bases.

     TALC.COL: A look-up table of the polygon attributes in TALC.E00.

     TALC.PNT: A look-up table of the point attributes in TALC_P.E00.

    Entity_and_Attribute_Detail_Citation:

      Database root name: TALC

      P1 VALUE AND LETTER SYMBOLS FOR GEOLOGIC UNITS MAPPED=======
CODE |   FEATURE
1, (Archean marble, no tag)
1,1
2,2/5
3,3
4,4/56
6,6
7,7
8,8
9,9/32
10,10
11,11
12,12
13,13
14,14
15,15
16,16
17,17
18,18
19,19
20,20
21,21
22,22
23,23
24,24
25,25
26,26
27,27
28,28
29,29
30,30
31,31
33,33
34,34
35,35
36,36
37,37
38,38
39,39
40,40
41,41
42,42
43,43
44,44
45,45
46,46
47,47
48,48
49,49
50,50
51,51
52,52
53,53
54,54
55,55
57,57

FEATURES IN THE DATABASE-------------------------
CODE |   FEATURE
010  | study area boundary
020  | map unit contact
500  | map label for site of talc mine, prospect, or occurrence

Distribution_Information:
  Distributor:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: U.S. Geological Survey, Mineral Resources Program

      Contact_Address: Bradley S. Van Gosen 
        Address_Type: mailing address
        Address: U.S. Geological Survey
        Address: MS 905, Box 25046, Denver Federal Center
        City: Lakewood
        State_or_Province: CO
        Postal_Code: 80225-0046
      Contact_Voice_Telephone: (303) 236-1566 office
      Contact_Voice_Telephone: (303) 236-1800 secretary (Joan Luce)
      Contact_Electronic_Mail_Address: bvangose@usgs.gov

  Distribution_Liability: Although this digital spatial data has been subjected to rigorous review
and is substantially complete, it is released on the condition that neither the USGS nor the United
States Government may be held liable for any damages resulting from its authorized or
unauthorized use.

  Standard_Order_Process:
    Digital_Form:
      Digital_Transfer_Information:
        Format_Name: ARC/INFO
        Format_Version_Number: Version 7.1.1
        Format_Version_Date: 1997
        File_Decompression_Technique: None
      Digital_Transfer_Option:
        Online_Option:
          Computer_Contact_Information:
            Network_Address
            Network_Resource_Name: http://greenwood.cr.usgs.gov
    Fees: None

Metadata_Reference_Information:
  Metadata_Date: 19981207
  Metadata_Review_Date: 19981207
  Metadata_Contact:
    Contact_Information:
      Contact_Person_Primary:
        Contact_Person: Bradley S. Van Gosen
        Contact_Organization: U.S. Geological Survey, Mineral Resources Program

      Contact_Address:
        Address_Type: mailing address
        Address: U.S. Geological Survey
        Address: MS 905, Box 25046, Denver Federal Center
        City: Lakewood
        State_or_Province: CO
        Postal_Code: 80225-0046
      Contact_Voice_Telephone: (303) 236-1566 office
      Contact_Voice_Telephone: (303) 236-1800 secretary (Joan Luce)
      Contact_Electronic_Mail_Address: bvangose@usgs.gov
  Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
  Metadata_Standard_Version: 19940608