Zonia Copper Oxide Project, Arizona
Geology & Mineralization
The Zonia property is in the southern part of the Basin and Range Transition province of the North American Cordillera, immediately south of the Colorado Plateau and north of the Basin and Range province. This section of the Basin and Range province in Arizona and New Mexico hosts a large number of base and precious metal mines and mineral occurrences. The Zonia deposit is hosted by the steeply dipping, northeast-trending, Precambrian Yavapai Series, which consists of schistose subvolcanic intrusions, volcanic flows, and tuffaceous sedimentary rocks. Portions of the area are covered by post-mineralization Quaternary basalt, fanglomerate, and alluvial material.
Rocks at the Zonia Property consist mainly of highly variably foliated quartz monzonite porphyry (dacite) subvolcanic rocks, diorite, and minor diabase dikes, with highly schistose phyllites and chlorite schist along the southeast margin. Foliation dips steeply to the northwest over most of the Zonia claims block, but changes to southeast dipping along the southeast margin in the Bragg Estate and Silver Queen claim block. This typical greenstone package is intruded and enclosed by younger Precambrian granitic batholiths which show only weak foliation at the margins.
Zonia appears is the highly oxidized portion of a previously supergene-enriched metamorphosed porphyry deposit, though it has also been interpreted as the stockwork zone of a volcanogenic massive sulfide (VMS) deposit in the past. The main mineralized unit is variably foliated quartz-feldspar porphyry and related sericite schist, with disseminated sulphides and stockwork quartz-sulphide veins that predominately pre-date the metamorphism, but also post-date it to some extent.
Oxidation of the original chalcopyrite mineralization and younger secondary supergene chalcocite has been pervasive and deep, extending down over 250 metres (874 feet) in the central pit at the historical Cuprite shaft. Chrysocolla, malachite, azurite, melaconite, and cuprite are the most common copper minerals. Quartz and jasper accompany the ore minerals; oxides are ubiquitous in the mineralized zones. Higher copper grades are associated with contacts of the quartz monzonite porphyry with acid-reactive mafic chlorite schist, which are zones of increased supergene deposition. Lower grades are associated with more massive enclosures of the dacite porphyry, which were less permeable to supergene fluids.