Special Publication Bureau of Mines Mineral Investigations in the Juneau Mining District, Alaska, 1984-1988 Volume 2.-Detailed Mine, Prospect, and Mineral Occurrence Descriptions Section B Glacier Bay Subarea UNITED STATES DEPARTMENT OF THE INTERIOR Special Publication Bureau of Mines Mineral Investigations in the Juneau Mining District, Alaska, 1984-1988 Volume 2.-Detailed Mine, Prospect, and Mineral Occurrence Descriptions Section B Glacier Bay Subarea By Jan C. Still UNITED STATES DEPARTMENT OF THE INTERIOR Manuel Lujan, Jr., Secretary BUREAU OF MINES T S Ary, Director GLACIER BAY SUBAREA CONTENTS Page Introduction ................................................................................. B-i Access ................................................................................. B-I Land status .................................................................................. B-i Acknowledgments .................................................................................. B-2 Previous studies ................................................................................. B-2 Present study .................................................................................. B-2 Mines, prospects, and occurrences . ................................................................................. B-2 Brady Glacier deposit ................................................................................. B-5 Introduction-history ................................................................................. B-5 Land status .................................................................................. B-5 Deposit description ................................................................................. B-5 Metallurgical test samples . .................................................................................. B-6 Identified resources ................................................................................. B-6 Orange Point deposit ................................................................................. B-13 Introduction-history ................. ................................................................. B-13 Deposit description ................................................................................. B-13 Metallurgical test samples . .................................................................................. B-14 Geophysics ................................................................................. B-14 Identified resources ................................................................................. B-14 Margerie Glacier deposit ............... .................................................................. B-17 Introduction-history ................ .................................................................. B-17 Present study ................................................................................. B-17 Deposit description ................................................................................. B-17 Identified resources .................................................................................. B-17 Nunatak Molybdenum deposit . ................................................................................. B-19 Introduction-history ............... .................................................................. B-19 Deposit description .................................................................................. B-19 Identified resources ................................................................................. B-19 Massive Chalcopyrite deposit . ................................................................................. B-19 Introduction-history ................ .................................................................. B-19 Deposit setting ................................................................................. B-22 Deposit description ................................................................................. B-22 Geophysics ................................................................................. B-28 Identified resources ................................................................................. B-28 LeRoy Mine ................................................................................. B-28 Introduction-history ............... ................................................................... B-28 Mine setting ...................................... B-28 Mine description .B-28............................................................................ Rainbow Mine ... ............................................... I. ............................ B-32 Introduction-history ... ............................................................................... B-32 Mine description .......... ............................................... ...................... B-32 Other mines, deposits, prospects, and occurrences ....................... ........................................... B-32 References ................................................................................. B-36 Appendix B-i-Results of 1985 investigations in the Johns Hopkins Inlet-Margerie Glacier area .......... B-37 Appendix B-2-Metallurgical test results on Brady Glacier deposit and Orange Point deposit ...... ........ B-49 Appendix B-3-Analytical results . .................................................................................. B-53 Appendix B-4-Nunatak Molybdenum deposit diamond drill hole and surface analytical results ..... ..... B-62 B-i ILLUSTRATIONS Page B-1. Glacier Bay subarea showing most important mines, deposits, prospects, and occurrences ........ B-3 B-2. Bureau employee collecting a metallurgical test sample from the Brady Glacier deposit ............ B-6 B-3. Idealized block diagram of Brady Glacier deposit ............. ............................................... B-7 B-4. Brady Glacier deposit showing claims, selected drill holes, ore, and the nunataks ..... .............. B-9 B-5. Idealized cross section through the Brady Glacier deposit .......... ........................................ B-il B-6. Bureau employees at the Orange Point deposit ................ ................................................ B-13 B-7. Orange Point deposit showing geology and sample locations ......... ..................................... B-15 B-8. Oblique aerial photograph of the Orange Point deposit showing Hills number 1 and 2 sample locations .................................................................................... B-16 B-9. Margerie Glacier deposit showing geology and sample locations ........ ................................. B-18 B-10. Nunatak molybdenum deposit showing geology, mineralized areas, and diamond drill hole locations .................................................................................... in pocket B-11. Nunatak molybdenum deposit, area of conspicuous molybdenite, showing sample locations ..... B-20 B- 12. Nunatak molybdenum deposit, Nunatak fault zone showing sample locations ...... .................. B-21 B-13. Massive Chalcopyrite deposit discovered by Bureau ............ .............................................. B-23 B-14. Magnetometer survey above the Massive Chalcopyrite deposit ......... .................................... B-24 B-15. Massive Chalcopyrite deposit area showing geology, mineralization, and sample locations ........ B-25 B-16. Oblique aerial photograph of the west side of the Massive Chalcopyrite deposit area, showing sample locations . .................................................................................... B-26 B-17. Massive Chalcopyrite deposit and vicinity, showing sample locations and magnetometer survey results ................ .................................................................... B-27 B-18. Reid Inlet gold area showing the setting for the LeRoy and Rainbow Mines ...... .................... B-29 B-19. LeRoy Mine showing workings, geology, and sample locations ........ ................................... B-30 B-20. Rainbow Mine showing workings, geology, and sample locations ....... ................................. B-33 B-1-1. Location and geologic setting of the Johns Hopkins Inlet-Margerie Study Area, Glacier Bay, Alaska .................................................................................... B-38 B-1-2. Geologic map and VLF survey line locations, Orange Point area, Glacier Bay, Alaska ..... ........ B-39 B-1-3. Iron-stained zones in Johns Hopkins Inlet-Margerie Glacier area, Glacier Bay, Alaska ..... ........ B-40 B-1-4. Geology in the vicinity of mineral occurrences within the John Hopkins Inlet-Margerie Glacier area, Glacier Bay, Alaska .................................................................................... in pocket B-1-5. Sample location map of Johns Hopkins Inlet-Margerie Glacier area, Glacier Bay, Alaska ......... in pocket B-1-6. Geologic and VLF line location map, Orange Point area, Glacier Bay, Alaska ..... .................. B-42 B-1-7. VLF lines over exposed massive sulfides, Orange Point, Glacier Bay, Alaska ...... .................... B-43 B-1-8. VLF survey lines north of Orange Point, Glacier Bay, Alaska ........ ..................................... B-44 TABLES B-1. Identified resources of the Nunatak Molybdenum deposit ......... ......................................... B-22 B-2. Other mines, prospects, and occurrences . ....................................................................... B-35 B-1-1. Analytical