Mineral Investigations on Baranof and Chichagof Islands, and Vicinity, Southeast Alaska, 1995
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U. S. Department of the Interior BlM-Alaska Open File Report 60 Bureau of Land Management BLWVAKlST-97/001+3090+930 October 1996 Alaska State Office 222 West 7th, #13 Anchorage, Alaska 99513 Mineral Investigations on Baranof and Chichagof Islands, and Vicinity, Southeast Alaska, 1995 Kenneth M. Maas, Peter E. Bittenbender, and Jan C. Still I . I Authors Kenneth M. Maas is a geologist in the Division of lands, Minerals and Resources working for the Juneau Minerals Resources Team, Bureau of Land Management, Juneau, Alaska. Peter E. Bettenbender is a geologist Division of Lands, Minerals and Resources working for the Juneau Minerals Resources Team, Bureau of Land Management, Juneau, Alaska. Jan C. Still is a mining engineer in the Division of Lands, Minerals and Resources working for the Juneau Minerals Resources Team, Bureau of Land Management, Juneau, Alaska. Cover Photo Dilapidated equipment and structures lie idle at the lucky Chance millsite, Silver Bay area of Baranof Island in Southeast Alaska. The mine was discovered by 1880 and the mill began operations by 1887, continuing on an intermittent basis until at least 1904. The lucky Chance Mine produced an unspecified quantity of gold and silver. (Photo by authors.) Open File Reports Open File Reports identifythe resultsofinventoriesorotherinvestigationsthat are madeavailabletothepublic outside the formal BlM-Alaska technical publication series. These reports can include preliminary or incomplete data and are not published and distributed in quantity. The reports are available at BlM offices in Alaska, the USDI Resources Library in Anchorage, various libraries of the Unversity of Alaska, and other selected locations. Copies are also available for inspection at the USDI Natural Resources Library in Washington, D.C. and at tre BLM Service Center Library in Denver. Mineral Investigations on Baranof and Chichagof Islands, and Vicinity, Southeast Alaska, 1995 Kenneth M. Maas Peter E. Bittenbender Jan C. Still Bureau of Land Management Open File Report 60 Alaska State Office October 1996 Anchorage, Alaska 99513 UNITED STATES DEPARTMENT OF THE INTERIOR BUREAU OF LAND MANAGEMENT MINERAL ASSESSMENT REPORT Mineral Investigations on Daranof and Chichagof Islands, and Vicinity, Southeast Alaska, 1995 Prepared By: i~Jr!~ ~'C~Qr2Qj (Signature) (Signature) Geologist Geologist (Title) (Title) (Title) September 27, 1996 September 27,1996 September 27, 1996 (Date) (Date) (Date) Technical Reviewers: Donald Baggs, BLM, Anchorage, AK Ron Baer, U.S.Forest Service, Sitka, AK John Kato, U.S. Forest Service, Juneau, AK > (Date) CONTENTS Pa~e Abstract 1 Executive Summary 2 Introduction ' 5 Purpose ofprogram. ........................................................ 5 Autllorities ......... 6 Priorities ............................................................. 7 Location and access .. 7 Land status .........................,................................... 7 Methodology ............................................................... 11 Acknowledgments ' 11 Previous studies 11 Mining history/production ...................................................... 16 General geology .............................................................. 18 Mineral deposit types .......................................................... 20 Bureau work ................................................................. 21 Hoonall road system '. 22 Gypsum Creek .................................................... 2~ East Point .......................................................... 23 Big Ledge . ~ . 23 Reconnaissan.ce ' 24, Hill Point 24 Tenakee ' 25 Slocum Am1 Molybdenum .' 25 Deep Bay 26 Rodman Bay 26 Kelp Bay 26 Sealion Cove 27 KrestofIsland . ~ ............................................. 27 Halleck Island 28 Magoun Island : 28 Siginaka Island " 29 WarIll Springs Bay 29 Silver Bay Area, Sitka 30 Gangola 30 Apex 31 Liberty 31 Edgecumbe Exploration Lode 31 Eureka 32 Lower Ledge 32 Stewart ' 33 i Unknown name 33 Bauer 33 Pinta Lake '. ................... .'. .......................... 34 Free Gold ............................................................. 34 Lucky Chance Mountain , 34 Lucky Chance 35 Goddard Hot Springs ........................................................ 35 Red BluffBay ~ 35 Patterson Bay .............................................................. 36 Snipe Bay ............................................................ ... 37 Redfish Bay 37 Port Lucy 37 Port Armstrong/Port Conclusion .. ............................................. 38 Conclusions 38 Bibliography 39 Appendix A. Analytical results for mines, prospects, and occurrences 67 Appendix B. Summary information for significant mines, prospects, and occurrences 92 TABLES 1. Deposits with medium to high mineral development potential . .. 3 2. Alaska Territorial Dept. ofMines and Minerals reports 14 3. Summary ofmine production ...................................."......... 17 A-I. Analytical results from mines, prospects, occurrences, and reconnaissance samples 70 A-2. Analytical results from REE sampling at Redfish Bay ' 90 A-3. Analytical results from carbonate sampling 90 A-4. Analytical detection limits by analytical technique " 91 B-1. Summary information for mines, prospects, and mineral occurrences 95 ILLUSTRATIONS 1. Location map ofthe Baranofand ChichagofIslands study area 8 2. Generalized land status map 9 3. Location and extent ofselected geologic maps and previous study areas 12 4. Sample location map ~ plate 5. Mines, prospects, and mineral occurrences ............................. plate 11 ~ I \ , I Mineral Investigations on Baranof and Chichagof Islands, and Vicinity, Southeast Alaska, 1995 ~y Kenneth M. Maas, Peter E. Bittenbender, and Jan C. Still ABSTRACT The Baranof and ChichagofIslands area is located along the northwest coast of Southeast Alaska. This area hosts historically significant producers of gold, silver, and gypsum. The Chichagof and Hirst Chichagof Mines, operating in Klag Bay and Kimshin Cove, were the main precious metal producers in the study area. Gypsum was produced by the Pacific Gypsum Company from a single mine operating in Iyoukeen Cove. U. S. Bureau ofMines personnel (who were subsequently incorporated into the Bureau ofLand Management) investigated mineral occurrences in the Baranof and Chichagof Islands area during 1995. This study will continue through 1996. Two crews examined 35 mines and prospects, and several additional sites were sampled in a reconnaissance fashion on Federal, State and private lands. In all, over 400 samples were taken for geochemical analysis, and 3,500 feet ofunderground workings were surveyed and mapped.. Work was concentrated around Silver Bay and along the Hoonah logging-road system. Several sites located along coastal areas were also visited. Detailed work was not performed in the West Chichagof and Klag Bay areas, as extensive studies were recently completed by Bureau personnel. Reference to these reports as well as a comprehensive list ofpublished and unpublished geologic and mineral resource reports are contained in the bibliography. Summary information is provided for 132 properties in the study area. Mineral development potential has been classified as low, medium or high for these properties. 'j j Results from the 1995 work define low-grade gold-bearing quartz veins in the Silver Bay area and the presence ofweakly mineralized skarn systems surrounding Gypsum Creek, north of r Freshwater Bay. No specific ore bodies were delineated from this work, although high-grade ) sphalerite mineralization was encountered at East Point, north ofTenakee Inlet. 1 f" I ." i EXECUTIVE SUMMARY !, Baranofand Chichagof Islands are located along the northwest coast of s.outheast Alaska. The present study encompassed these islands as well as the smaller islands to the west. Work completed in 1995 was conducted by U.S. Bureau ofMines geologists and el?-gineers. This study is part ofan ongoing statewide mineral land assessment authorized under Section 1010 ofthe Alaska National Interest Lands Conservation Act. Significant quantities ofgold, silver, and gypsum have been produced from this area; it was historically the second largest lode-gold producing area in Alaska. The Chichagof and Hirst-ChichagofMines produced the majority of r the gold and silver, and the Pacific Coast Gypsum Company's mine at Iyo~een Cove produced the gypsum. ! Two crews investigated 35 mines and prospects, and several additional sites were sampled in a reconnaissance fashion on Federal, State and private lands. In all, over 400 samples were taken for geochemical analysis, and 3,500 feet ofunderground workings were surveyed and mapped ,,;r during 1995. Efforts during 1995 were concentrated in the Silver Bay area and along the Hoonah logging road system as well as in scattered locations throughout the study area. Work was not performed in the West Chichagofand Klag Bay areas as extensive studies have already been completed. Results from the 1995 work indicate the low-grade nature ofgold-bearing quartz veins in the Silver Bay area and the presence ofskarn-related mineralization surrounding Gypsum Creek. No specific ore bodies were delineated from this work. A total of 135 mineral properties are recapped in the summary table presented at the end ofthis report. These properties are ranked by mineral development potential (MOP) to provide a basis for comparison. Nineteen properties were assigned a medium, medium to high, or high MDP ranking. Seven properties are ranked with a low-medium MDP and the remaining