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Podiform Chromite Deposits—Database and Grade and Tonnage Models

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Podiform Chromite Deposits—Database and Grade and Tonnage Models Podiform Chromite Deposits—Database and Grade and Tonnage Models Scientific Investigations Report 2012–5157 U.S. Department of the Interior U.S. Geological Survey COVER View of the abandoned Chrome Concentrating Company mill, opened in 1917, near the No. 5 chromite mine in Del Puerto Canyon, Stanislaus County, California (USGS photograph by Dan Mosier, 1972). Insets show (upper right) specimen of massive chromite ore from the Pillikin mine, El Dorado County, California, and (lower left) specimen showing disseminated layers of chromite in dunite from the No. 5 mine, Stanislaus County, California (USGS photographs by Dan Mosier, 2012). Podiform Chromite Deposits—Database and Grade and Tonnage Models By Dan L. Mosier, Donald A. Singer, Barry C. Moring, and John P. Galloway Scientific Investigations Report 2012-5157 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior KEN SALAZAR, Secretary U.S. Geological Survey Marcia K. McNutt, Director U.S. Geological Survey, Reston, Virginia: 2012 This report and any updates to it are available online at: http://pubs.usgs.gov/sir/2012/5157/ For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment—visit http://www.usgs.gov or call 1–888–ASK–USGS For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprod To order this and other USGS information products, visit http://store.usgs.gov Suggested citation: Mosier, D.L., Singer, D.A., Moring, B.C., and Galloway, J.P., 2012, Podiform chromite deposits—database and grade and tonnage models: U.S. Geological Survey Scientific Investigations Report 2012-5157, 45 p. and database. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted material contained within this report. iii Contents Abstract ...........................................................................................................................................................1 Introduction.....................................................................................................................................................1 Podiform Chromite Deposits ........................................................................................................................2 General Definitions ...............................................................................................................................2 Host Rocks and Structure ...................................................................................................................3 Morphology ............................................................................................................................................3 Ore Textures ...........................................................................................................................................3 Mineralogy .............................................................................................................................................4 Orgin .......................................................................................................................................................4 Exploration and Exploitation ...............................................................................................................4 Ore Types ................................................................................................................................................5 Rules Used ......................................................................................................................................................5 Classification of Podiform Chromite Subtypes .........................................................................................9 Preliminary Analysis ....................................................................................................................................10 Grade and Tonnage Models ..............................................................................................................10 Conclusions...................................................................................................................................................20 Explanation of Data Fields ..........................................................................................................................20 Location Maps ..............................................................................................................................................22 Acknowledgments .......................................................................................................................................34 References ....................................................................................................................................................34 Appendix A. Summary Statistics For Podiform Chromite Grade-Tonnage Models ..........................40 Appendix B. Deposit Model Country Codes and Country Names ........................................................45 Figures 1. World map showing the distribution of podiform chromite deposits used in this study.. .......2 2. Geologic map of the Masinloc mine, Zambales Province, Philippines, showing the chro- mite ore bodies grouped into chromite deposits based on the 100-meter rule .................7 3. Illustrations of an ophiolite stratigraphic column showing the zones with lithologies and distribution of podiform chromite ...............................................................................................8 4. Box plots of deposit tonnages by podiform chromite deposit subtypes .................................11 5. Cumulative frequency of ore tonnages of major podiform chromite deposits .......................14 6. Cumulative frequency of chromic oxide grades of major podiform chromite deposits ........14 7. Cumulative frequency plots of rhodium, iridium, ruthenium, palladium, and platinum grades of major podiform chromite deposits .........................................................................15 8. Cumulative frequency of ore tonnages of minor podiform chromite deposits .......................16 9. Cumulative frequency of chromic oxide grades of minor podiform chromite deposits ........16 10. Cumulative frequency plots of rhodium, iridium, ruthenium, palladium, and platinum grades of minor podiform chromite deposits .........................................................................17 11. Cumulative frequency of ore tonnages of banded podiform chromite deposits ....................18 iv 12. Cumulative frequency of chromic oxide grades of banded podiform chromite deposits ......................................................................................................18 13. Cumulative frequency plots of rhodium, iridium, ruthenium, palladium, and platinum of banded podiform chromite deposits ........................................................................................19 14. Map showing the distribution of podiform chromite deposit subtypes in Northern California, Oregon, and Washington, U.S.A. ..........................................................................23 15. Map showing the distribution of podiform chromite deposit subtypes in Southern Oregon and Northern California, U.S.A. ............................................................24 16. Map showing the distribution of podiform chromite deposit subtypes in Central California, U.S.A. .........................................................................................................................25 17. Map showing the distribution of podiform chromite deposit subtypes in Pennsylvania, Maryland, North Carolina, and Georgia, U.S.A. .....................................................................26 18. Map showing the distribution of podiform chromite deposit subtypes in Alaska, U.S.A .. .......................................................................................................27 19. Map showing the distribution of podiform chromite deposit subtypes in Quebec, Canada .....................................................................................................................28 20. Map showing the distribution of podiform chromite deposit subtypes in Newfoundland, Canada. ........................................................................................................29 21. Map showing the distribution of podiform chromite deposit subtypes in Cuba ....................30 22. Map showing the distribution of podiform chromite deposit subtypes in New Caledonia ......................................................................................................31 23. Map showing the distribution of podiform chromite deposit subtypes in the Philippines. ........................................................................................................................32 24. Map showing the distribution of podiform chromite deposit subtypes in Greece, Cyprus, and Turkey. .................................................................................................33 Tables 1. Specifications for chromite ore compiled from DeYoung and others (1984), Harben (2004), and U.S. Business and Defense Services Administration
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