fu\fE-199 UNITED STATES ATOMIC ENERGY COMMISSION GRAND JUNCTION OPERATIONS OFFICE EXPLORATION DIVISION SUMMARY OF URANIUM EXPLORATION IN THE LUKACHUKAI MOUNTAINS, APACHE COUNTY, ARIZONA 1950-1955 CONTRACT NOS. AT(30-1) 1021, 1139, 1263, 1364; AT(05-l) 234, 257 By Raymond F. Kosatka UNEDITED MANUSCRIPT Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed in this report, or represents that its use would not infringe privately owned rights. Reference therein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. March 30, 1956 Grand Junction, Colorado Summary of Uranium Exploration In The Lukachukai Mountains, Apache County, Arizona 1950 - 1955 CONTENTS Abstract ............................................................... iii Introduction. ••••••••••••• 0 ..................................... l Exploration and Mining History...................................... 1 Genera 1 Geology.. • • • • • • • • • • .. • • • • • • • • • • • • • • • .. • • • • • • • • • • • • • • • • • • • • 2 Sedimentary Rocks. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • .. • • 4 Igneous Rocks. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 4 Tectonic Structures .......................................... 7 Geologic History. 7 Economic Geology ••••••••••• 7 Mineralogy ••••••••••••• .................... 8 Ore Occurrences •••••••• 8 Types of deposits ••••••••••••••••••••••••••••••••••••••••••• 9 Sandstone lens deposits ••••••••••••••••••••••••••••••••• 9 Mudstone deposits ••••••••••••••••••••••••••••••••••••••• 9 Lithologic Variations in the Ore Unit •••••••••••••••••••••• 9 Size of Ore Deposits ••••••••••••••••••••••••••••••••••••••• 10 Color Alteration •••••••••••••••••••••••••••••••••••••••••••• 10 Ore Guides .................................................. 10 Exploration Methods ............................................. ll Reconnaissance •••••••••••••••••••••••••••••••••••••••••••••• ll Mapping of sedimentary trends ••••••••••••••••••••••••••• 12 Mine mapping............ • •••••••••••••••••••••••••• 12 Drilling Program............ ~···········o•o••oo•••••••• l3 Plan of Drilling •••••••••••••••••••••• o ••••••••••••••••• o ••• 14 Subsurface Mapping ••••••••••••••••••••• o •• o ••••••••••••• 15 Comparison of various types of subsurface maps •••••••••• 17 Results Of The Exploration Program •••••••••••••••••••••••••••••• 17 Northeast Rim ••••••••••••••••••••••••••••••••••••••••••••••• 18 Southwest Rim •••••••••• ••••••••••••••• 0 •••• 0 ............... 18 Center Peak area •• 18 Summary and Conclusions. ...................... 0 ............... 0 ••• 19 References ......................................................... 23 i ILLUSTRATIONS Figure l Index map of the Four Corners region •••••••••••••••••• 3 Figure 2 Geologic map of the Lukachukai Hountains area, Apache County Arizona .•..••••..•.•..••••....•.•• appended Figure 3 Tectonic map, Four Corners region .•..•..••••••••••••.• 5 Figure 4 Representative section of rocks exposed in the Lukachukai Mountains area ••.••.••.•••..•.••••.• 6 Figure 5 Structure contour, sedimentary trend, joint, and ore deposit map of the Lukachukai Hountains Arizona ........•.••....•......................•..•.•.• appended Table 1 Summary of drilling statistics ••.•••••••••••••.•.••••• 20 Table 2 AEC reports. • • • . • . • . • • . • . • . 21 ii ABSTRACT The U. S. Atomic Energy Commission carried on an exploration program of reconnaissance and drilling in the Lukachukai Hountains, Apache County, Arizona, from September 1950, until August 1955. Objectives of this program were fourfold: (1) to find mineable deposits of uranium ore (2) to develop sufficient reserves to justify construction of a processing mill at Shiprock, New Mexico, (3) to discover and develop ore-finding criteria, ore trends and favorable ground and (4) to evaluate the ore potential of the Lukachukai Mountains. Uranium ore was found within a 50-foot unit of the Salt Wash member of the Harrison formation, approximately 45 feet above the Salt Wash-Bluff contact. Radioactivity of the ore deposits in the Lukachukai Mountains is in equilibrium and the ore minerals are secondary in origin, principally carnotite and tyuyamunite. Ore bearing sandstones commonly lie between impervious mudstones and have finely disseminated organic matter, calcium carbonate, and iron and manganese oxides associated with the ore. Most ore bodies are in clusters elongated parallel to direction of ancient stream flow, and most uranium is confined to the more permeable portions of sand­ stone lenses filling scours in Salt Wash stream channels. Tectonic structure has not apparently influenced local deposition of uranium. A total of 374,198 feet was drilled in 1,837 holes, 242 of which were in ore and 469 mineralized. iii INTRODUCTION The Lukachukai Mountains are at 36° 30' north latitude and 1090 15' west longitude near Cove School, Apache County, Arizona, (Fig. l). The Atomic Energy Commission camp at Cove School is reached by 35 miles of graded gravel road which joins U. S. Highway 666 approximately 8 miles south of Shiprock, New Mexico. Any one of three gravel roads from the camp leads to the drilling area where the three connect. An airstrip, for small planes, is located about 3 miles east of Cove School. All of the Lukachukai Mountains lie within the Navajo Indian Reservation, and the land is administered by the Navajo Tribal Council. Leases and/or mining permits are held by members of the Navajo Tribe and are assigned to private operators. Navajo Uranium Division of Kerr-McGee Oil Industries, Inc., Climax Uranium Company, Walter Duncan Mining Company, Price Exploration Company and Great States Uranium Corporation all have leases and/or mining permits in the drilling area. The successful completion of the program was made possible by the cooper­ ation of personnel of the Atomic Energy Commission, Walker-Lybarger Construc­ tion Company, drilling contractors, and mine operators in the area, and this cooperation is gratefully acknowledged. EXPLORATION AND MINING HISTORY In the fall of 1949, F. A. Sitton of Dove Creek, Colorado, became interested in properties claimed by two Navajos, DanK. Phillips and Kaley Black, on which mineralized outcrops occurred. After it became apparent from further prospecting of rims in the area that large tonnages of uranium ore could be postulated for the leases, Mr. Sitton negotiated leases for exploitation of the properties and began construction of access roads to the most favorable outcrop in preparation for mining. In June 1950, F.A. Sutton, Inc. made the initial ore shipment from Kaley Black's lease on Mesa I. The initial shipment from Dan Phillips lease on Hesa II was made in November 1950. Late in 1950, Hr. Sutton and Richard 0. Dulaney Jr., also of Dove Greek, Colorado, formed the Navajo Uranium Company and expanded mining operations in the Lukachukais. The Navajo Uranium Company was purchased by Kerr-HcGee Oil Industries, Inc. in Hay 1952. Frank Nacheenbetah located promising outcrops on Hesa IV l/2 during the summer of 1950, and after assigning his mining permit to Climax Uranium Company, began shipments in April 1951. The early shipments were made to the AEC ore buying station at Honticello, Utah. The AEG opened an ore buying station at Shiprock, New Hexico in January 1952. In July 1952, Walter Duncan Mining Company began ore shipments from Willie Cisco's mining permit on Three Point Hesa. On August 17, 1953 Kerr-HcGee Oil Industries, Navajo Uranium Division signed a contract with the AEC to produce uranium concentrates from a mill to be built at Shiprock. The mill began operating in October 1954. In 1955 there were ll operating mines in the Lukachukai Mountains. 1 The room and pillar system has been the principal m1n1ng method but rim stripping and open pit mining have also been used to develop surface outcrops on rims. The mine operators in the area have all done core, non core, and underground long hole drilling. The Lukachukai Mountains area was brought to the attention of the Atomic Energy Commission by Mr. Sitton in 1950, and following preliminary examina­ tion by geologists of the Grand Junction Exploration Division, an exploration program of reconnaissance and drilling was begun by the Commission. The objectives of this program have been: (1) To find mineable bodies of uranium ore, (2) to develop sufficient reserves of uranium ore in the areas drilled, by direct delimitation of ore bodies with drill holes, to warrant construction of a 100 ton capacity mill at Shiprock, New Mexico, (3) to discover and develop criteria indicative of ore, ore trends and favorable areas, which would result in geologic informa­ tion that could be used to evaluate the ore potential of the Lukachukai Mountains and would aid future private exploration and mining in this and adjoining areas. GENERAL GEOLOGY The Lukachukai Mountains, covering an area of approximately 72 square miles, are the northernmost extension of the