New Mexico

Ambrosia Lake – Treeline

Project Highlights

Project Details

Project Overview

The Ambrosia Lake – Treeline Property consists of deeded mineral rights totaling 24,555 acres and a mining lease along with certain unpatented mining claims covering approximately 1,700 acres. The project is located approximately 115 miles west-northwest of Albuquerque, in McKinley and Cibola Counties, Grants Uranium District, New Mexico.

The project is situated within the boundaries of the Ambrosia Lake mining district, which is the largest uranium mining area (in terms of pounds of U3O8 production) in the United States. Initial exploration for sandstone-hosted uranium deposits started in the early 1950s while commercial production commenced in the mid-1950s and continued uninterrupted until the late 1990s. During the active mining period of the Ambrosia Lake mining district nearly 22 million pounds of U3O8 were produced from eight mines on Company-owned properties in the project area.

Mineral Resources

There are no current Mineral Reserves or Mineral Resources on the Ambrosia Lake – Treeline property. Further compilation of the historic geological and drilling data, resource modelling and possible confirmation drilling will be necessary to convert the historic estimates outlined below to NI 43-101 compliant resources/reserves.

Geology and Mineralization

The Ambrosia Lake – Treeline Project lies on the Chaco Slope of the 100-mile wide San Juan Sedimentary Basin. The basin is filled with up to 15,000 feet of Paleozoic and Mesozoic sediments consisting predominantly of sandstone, siltstone and shale with minor limestone. The basin is asymmetric with the southern limb dipping gently to the north and the northern limb dipping steeply to the south.

Within the basin, the Jurassic Morrison Formation is the primary host for the uranium mineralization. The Morrison Formation is divided into three members. The lowest is the 255 foot thick Recapture Shale Member which is overlain by the 350 foot thick Westwater Member, which in turn is overlain by the 115 foot thick Brushy Basin Shale. The Westwater Member is the host to significant uranium mineralization. It is composed of a fine- to coarse-grained, poorly sorted, feldspathic sandstone with conglomeritic zones and minor discontinuous mudstone and shale units.

The sandstone units of the Westwater Member strike west-northwest and dip gently to the northeast. The units are generally oxidized up dip and to the south of the mineralized zone and reduced down dip and to the north of the mineralized zone. The oxidized units are generally reddish-brown from the iron content, whereas the reduced units are generally green to grey due to the organic compounds, reduced iron compounds, or clay-chlorite assemblages.

Historical Exploration

Considerable exploration and mining has been carried out on lands that make up the project and on adjoining properties, and this activity continued for an extended period from the 1950s through the late 1990s.

Utah Construction, Kerr McGee, Teton UNC, and UNC-Homestake Partners drilled on the land Sections comprising the Ambrosia Lake Project. EnCore possesses what are thought to be nearly complete and map and drill-hole log files, except for some of the UNC-Homestake Partners logs.

enCore Energy has not done sufficient work to classify the historical estimates as current mineral resources or mineral reserves, and they should not be relied upon. A qualified person has not done sufficient work for enCore to classify the historical estimate as a current mineral resource estimate. The Company does not treat this historical estimate as a current mineral resource estimate, and the estimate should not be relied upon.

Property (Section,Township, Range)Tons1Grade; % U3O8 Pounds, U3O8
13 -13N – 9W259,0000.16855,313(2)
17 -13N – 9W149,0000.06631,263(3)
5-14N – 10W327,7240.105688,913(4)
7-14N-10W160,4780.174630,425(5)
23-14N – 10W211,0580.291,211,502(6)
25-14N – 10W158,6320.17538,375(7)
27 -14N – 10W170,0000.311,050,000(8)
Treeline593,4480.131,500,000(9)
Total2,029,3400.1267,105,791
  1. 15 cubic ft per ton.
  2. Sec 13-13N-9W estimated by Nelson, Jon, Uranium Resources Inc., June 29, 2007, in Wilton, Dean, CPG, March 30, 2018, Technical Report on the Ambrosia Lake Uranium Project, McKinley County, N.M., Westwater Resources Inc, Centennial, Colorado. Cutoff at 6 feet of 0.10%; . Circle tangent method with maximum radius of 50 feet.
  3. Sec 17-13N-9W estimated by Nelson, Jon, Uranium Resources Inc., January 18, 2008, in Wilton, Dean, CPG, March 30, 2018, See note 2, Cutoff at 0.03% and 0.3 grade x thickness; . Circle tangent method with maximum radius of 50 feet.
  4. Sec 5-14N-10W estimated by Pathfinder Mines, 1980, Mine Plan, in Wilton, Dean, CPG, March 30, 2018, See note 2 above, “diluted to 6 feet at zero grade”, Proven and Potential Reserves.
  5. Sec 7-14N-10W estimated by Pathfinder Mines, 1980, Mine Plan, in Wilton, Dean, CPG, March 30, 2018, See note 2 above, “diluted to 6 feet at zero grade”, Proven and Potential Reserves
  6. Sec 23-14N-10W estimated by Yancy & Associates, May 1997, Mine Plan – Sections 23 and 25 Ambrosia Lake, New Mexico, for Rio Algom Mining Corporation, Quivira Mining Company, in Wilton, Dean, CPG, March 30, 2018, see note 2 above, Reported as Remaining Reserves estimated by “mapped stope development” with thicknesses ranging from 7 feet to 48 feet.
  7. Sec 25-14N-10W estimated by Yancy & Associates, May 1997, Mine Plan – Sections 23 and 25 Ambrosia Lake, New Mexico, for Rio Algom Mining Corporation, Quivira Mining Company, in Wilton, Dean, CPG, March 30, 2018, see note 2 above, Reported as Remaining Reserves estimated by “mapped stope development” with thicknesses ranging from 11 feet to 25 feet. 
  8. Sec 27-14N-10W estimated by Capitan, Melvin, Feb 25, 2008, Uranium Resources Inc., “Ore Reserve Calculation Sheet 3, T14N R10W Section 27”, in Maxwell, Robert, CPG and Bernard Guarnera, March 1, 2010, Technical Report on Ambrosia Lake Project, Section 27, et al., Behre Dolbear Report  07-019, reported as Indicated Resources, Cutoff = 0.04%, and 0.04% grade x thickness; . Circle tangent method with maximum radius of 50 feet.
  9. Tree Line Project, 61 Unpatented mineral claims in Sections 25 & 30 T13N R9W; Sec 29 and 30 T13N R8W and Sec 26 T14N R10W and lease of part of Sec 24 T13N R9W; Conoco Inc.,1978, Internal mine planning memo, Cutoff = 6 feet of 0.05% U3O8 , unclassified category of historic resources.

A qualified person has not done sufficient work for enCore to classify the historical estimate as a current mineral resource estimate. The Company does not treat this historical estimate as a current mineral resource estimate, and the estimate should not be relied upon.

Douglas H. Underhill, PhD, CPG, enCore’s Chief Geologist, is the Qualified Person as defined under National Instrument 43-101 and has reviewed and verified the information presented throughout this enCore Energy website.