Prospect, Active

Commodities and mineralogy

Main commodities Ag; Au; Cu
Other commodities As; Pb; Sb; Zn
Ore minerals arsenopyrite; chalcopyrite; galena; gold; pyrite; pyrrhotite; sphalerite; stibnite
Gangue minerals ankerite; quartz

Geographic location

Quadrangle map, 1:250,000-scale HE
Quadrangle map, 1:63,360-scale A-6
Latitude 63.216
Longitude -149.643
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Mayflower prospect is at an elevation of about 3,400 feet, on the west side of Bryn Mawr Creek. It is in the NW1/4 of sec. 3, T. 20 S., R. 11 W., of the Fairbanks Meridian. The location is accurate to within 400 feet.

Geologic setting

Geologic description

The country rocks in the area of the Mayflower prospect include Devonian to Triassic clastic, carbonate, volcanic, and volcaniclastic strata, which are intruded by a plug and dikes of Upper Cretaceous (70-65 Ma) quartz diorite porphyry (Swainbank and others, 1977). The Mayflower prospect is associated with a dike-like extension of the intrusive plug at the Golden Zone mine (HE043). Major faults trend northeast-southwest and have imparted a strong northeast-trending fabric to the host rocks. These faults have controlled the emplacement of intrusive rocks. At the Mayflower there is evidence that northwest-trending faults predated intrusion, as the dike trends northwest before swinging back to the northeast. The northwest-trending shear zone was also important during mineralization (unpublished report by Addwest Minerals International Ltd., 1997).
There are three types of deposits: sulfide disseminations, veins, and skarns. The dike contains disseminated sulfides and stockwork quartz-sulfide veinlets. Limonite and ankerite alteration is widespread. Adjacent to the dike, calc-silcate skarn bodies up to 15 feet thick contain 0.1 ounce of gold per ton and 10 percent combined lead and zinc. The skarn comprises pyrrhotite, pyrite, chalcopyrite, and arsenopyrite (up to 10 percent by volume) in a epidote, garnet, and actinolite (unpublished report by Addwest Minerals International Ltd., 1997).
Geologic map unit (-149.645291542539, 63.2155261564423)
Mineral deposit model Combination of polymetallic vein and Au-Ag breccia pipe or Cu-Au porphyry (Cox and Singer, 1986; models 22c, 20c), with Cu skarn (Cox and Singer, 1986; model 18b)
Mineral deposit model number 22c, 20c, 18b
Age of mineralization The Mayflower prospect is a satellite of the nearby Golden Zone mine (HE043) which has been dated at 70-65 Ma (Late Cretaceous) (Swainbank and others, 1977).
Alteration of deposit Alteration consists of a combination of skarn (epidote, garnet and actinolite), silica flooding, ankerite, pyrite and sericite. Limonite and uncommon chalcocite are oxidation and supergene mineral assemblages.

Production and reserves

Workings or exploration
The Mayflower prospect comprises two claims adjoining the Golden Zone on the north and was developed only by a few pits at the time of Ross’s (1933) visit. The rock is brecciated, iron-stained, and soaked with quartz, so that identification is difficult, but it appears to be, at least in part, a continuation of the fine-grained intrusive mass of the Golden Zone (HE043). The lode can be traced with fair accuracy by means of the pits for a length of 350 feet trending N 30-35 E and dipping 70 SE. One of the pits shows mineralization off the line of this lode. The most northerly pit is the largest and the only one in which bedrock was satisfactorily exposed at the time of Ross’s visit. There the well-mineralized part of the zone of shearing and brecciation was 32 inches wide. A sample across it yielded on assay 0.07 ounce of gold and 2.60 ounces of silver to the ton. Some specimens from the pit contain considerable chalcopyrite, but the average copper content of the lode as exposed was low. Samples collected by Henry Stevens of the Bureau of Mines in 1929, yielded the between 0.06 and 0.34 ounces of gold and 1.20 to 15.80 ounces of silver to the ton and as much 5.3 percent copper.
The prospect was explored by a reconnaissance IP and CS-AMT survey and by 1,500 feet of trenching. One shallow shaft was dug (during the 1930s?) and since has collapsed (Hawley and Clark, 1974).
Indication of production Undetermined

Additional comments

See Golden Zone mine (HE043).