CONGRESS
Location:
Yavapai County, Arizona, approximately 60 miles NW of Phoenix
Minerals:
Gold and Copper
Area:
260 Acres
Ownership
90%
Status:
Exploration/Drilling
Summary and Background
Historically Arizona’s largest gold-silver mine, and with production of approximately 500,000 ounces of gold (average grade of 0.284 ounces per ton), Congress operated at intervals from 1880 until 1992. At shutdown, with gold trading around $360 per ounce, the mine was still producing gold at a reported average grade of .228 ounces per ton. (The Republic Goldfields 1991 Annual Report lists production of 125,000 tons, yielding 28,500 ounces of gold.)
Potential for Additional Resources
A March, 2019 Technical Report by Mine Mappers L.L.C. and Mark Osterberg, Registered Professional Geologist states: “The historical operations at the Congress mine provide strong evidence that additional mining resources, similar in character to those mined in the past, should be amenable to efficient and cost-effective recovery.”*
Osterberg also notes: “It is probable that the resource left by the 1990-1992 operations of the Republic Goldfields New Congress mining operation would be very attractive to mining companies active in the western U.S.”*
Summary and Background
Casa’s exploration team has compiled historic property data and, in the field, has identified and mapped vein systems and other areas of potential resources now under exploration as part of the 10,000-foot drill program. The program was designed to provide new information in the area of historically reported gold occurrences, confirm reported historic drill results and provide hard data in places where previous mine operators outlined production stopes that were never developed.
Drilling is focused on the western extent of the property’s Congress and Niagara veins. In the 2022 calendar year Casa may, at its option, exceed the initial contract footage.
Casa’s field work has successfully located many historic drill hole collars as well as the shaft system on the Congress Gold Mine property but available records are incomplete. Drill hole information will supplement the Company’s compilation and allow for an accelerated and more comprehensive re-evaluation of gold, silver and copper values and distribution as well as direct work into areas that may host mineable values and structures.
Copper-Gold Porphyry Potential
The gold veining systems, along with investigations by Casa, indicate the presence of porphyry-style copper-gold mineralization. Historically, the property was never explored with porphyry potential in mind. Casa will investigate this potential further.
Source: NI 43-101 Technical Report, Congress Mine Patented Claims, Yavapai County, Arizona, USA, by Mine Mappers LLC and Mark Osterberg, Ph.D. Historical information based on numerous historical reports and compilations available from public sources, including Malartic High Grade and Echo Bay Mines. The 1991 annual report of Republic Goldfields lists production at Congress of 125,000 tons yielding 28,500 ounces of gold, equivalent to an average grade of .228 ounces per ton. The potential quantity and grade is conceptual in nature. There has been insufficient exploration to define a mineral resource and it is uncertain if further exploration will result in the target being delineated as a mineral resource.
History
Historically One of Arizona’s Most Important Gold Mines*
The Congress mine has a well-known, long history dating from 1887. Between 1880 and 1980, an estimated 1.5 million tons of ore was milled at an overall grade of 0.284 ounces per ton, producing 426,000 ounces of gold. In 1981, The Congress Consolidated Gold Mining Company optioned their property to the Magic Circle Energy Corporation. Magic Circle Energy Corporation subsequently drilled approximately 100 exploration core holes and defined an unclassified “reserve” consisting of 350,000 tons at a grade of 0.28 ounces per ton (Pay Dirt, September 1984).
Echo Bay Mines
Magic Circle Energy then entered into a Joint Venture agreement with Echo Bay Mines who expanded, developed and mined out the resource. Echo Bay did not find adequate additional reserves and shut down the mining operation in 1988. Their estimated production was likely less than 75,000 ounces gold.
Malartic Hygrade and Republic Goldfields
Malartic Hygrade Gold Mines purchased the Congress mine property from Echo Bay in 1989. The company subsequently drilled a number of core holes, defined a minable reserve and constructed a 500 ton per day underground mining operation. The company changed their name to Republic Goldfields, Inc in June of 1991 and operated the mine into 1992. Their estimated production was less than 50,000 ounces gold.
Neither significant exploration, development nor operations have occurred since the closure of the Republic Goldfields operation.
Source: NI 43-101 Technical Report, Congress Mine Patented Claims, Yavapai County, Arizona, USA, by Mine Mappers LLC and Mark Osterberg, Ph.D. Historical information based on numerous historical reports and compilations available from public sources, including Malartic High Grade and Echo Bay Mines. The 1991 annual report of Republic Goldfields lists production at Congress of 125,000 tons yielding 28,500 ounces of gold, equivalent to an average grade of .228 ounces per ton. The potential quantity and grade is conceptual in nature. There has been insufficient exploration to define a mineral resource and it is uncertain if further exploration will result in the target being delineated as a mineral resource.
Geology
Proterozoic igneous and metamorphic rocks crop out throughout the area and comprise the basement for the region. These rocks are coarse-grained, foliated granites, gneisses and amphibolites. The granites and gneisses are characterized by equigranular and megacrystic, igneous textures; the amphibolites by darker colored, foliated masses of biotite and amphibole.
These rocks are intruded by fine-grained aplitic and lamprophyric dikes and sills and white bull quartz veins, pods and masses are widely scattered throughout the sequences. The granites are intruded by younger stocks, most notable are the Laramide-age, intermediate stocks that host porphyry copper mineralization at Bagdad, Arizona and the Congress Cu-Mo porphyry located immediately to the northwest of the historic Congress mine.
Gold mineralization in the Martinez district, and in the Congress Mine itself, is concentrated along a series of composite quartz-greenstone structural zones that strike, generally in a northwest-southeast direction with modest dips to the northeast. Historic production has come entirely from the Congress Greenstone Dike and the Niagara Vein Zone (Figure 3). The plan outlines of the historical workings in both veins, presumed to mimic the “paying ore shoots”, plunge slightly west of north to depths of approximately 2000-feet along the structural zone, oblique to the strike and dip of the structural system. Mineralization is reportedly contained in quartz veins generally emplaced along the footwall of the dike and vein zone respectively.
The Congress fissure occurs within a 15-foot wide “greenstone” dike and dips 20° to 30° to the northeast. The vein fillings consist of massive, coarse-textured, grayish-white quartz that contains irregular masses, bands, and disseminations of fine-grained pyrite with minor galena, chalcopyrite and limonite-hematite-geothite (Herald and Russ, 1985).
The Niagara Vein Zone is characterized by a more extensive development of quartz and is generally of lower gold grade than in the Congress Greenstone Dike. It also contains more galena and higher silver grades (Rehrig and Wilson, 1985).
