The Pollyanna deposit is located near the eastern margin of the Stikine Terrane west of Granite Mountain in south-central British Columbia. The Stikine Terrane is dominantly oceanic and became amalgamated with the Quesnel Terrane to the east probably during Triassic times. The dominant rock types in the region are metabasalt, limestone and argillaceous metasediments of the Mississippian to Triassic Cache Creek Group. These are intruded by the dioritic to quartz dioritic Late Triassic Granite Mountain pluton and the (?)Cretaceous Sheridan Creek pluton. The Granite Mountain pluton has been dated at 204 +/- 6 Ma by potassium-argon dating of hornblende (CIM Special Volume 15 page 195). Jurassic sedimentary rocks overlap both the Cache Creek and Quesnel terranes to the north and east of the plutons. Older rocks are largely obscured by Plateau Basalt of probable Miocene age, to the west.

The Granite Mountain pluton has been affected by regional metamorphism (greenschist facies) and deformation along with the enclosing Cache Creek Group. The Cache Creek Group and the margins of the Granite Mountain pluton record effects of ductile deformation. The main body of the pluton has been cataclastically deformed.

The Pollyanna deposit is one of the five orebodies that comprise the Gibraltar mine, the others are: Granite Lake (093B 013), Gibraltar West (093B 007), Gibraltar North (093B 011) and Gibraltar East (093B 012). The orebodies are hosted by the Granite Mountain pluton with ore mineralization almost entirely confined to the Mine Phase Tonalite portion of the Granite Mountain pluton. The Mine Phase Tonalite appears to form a thin outer shell about the main body of the pluton and contains approximately 30 per cent quartz, 50 per cent saussuritized plagioclase feldspar and 20 per cent chlorite. Varying degrees and types of alteration are present and readily visible in the Mine Phase Tonalite. Economic sulphide mineralization in the Mine Phase Tonalite is usually associated with sericitization and chloritization. The tonalite has been strongly deformed by shearing and mineralization is strongly associated with this deformation. Mineralization is generally accompanied by alteration and is confined to deformational structures. These structures comprise small and large shear zones, foliation planes, short veins and various dilatant structures.

As a whole, the Gibraltar mineralized system is comprised of numerous structural hosts for economic mineralization ranging from highly mineralized shear zones to complex sets of sheeted shear veins commonly referred to as oriented stockworks. The oriented stockwork is the prevalent structural host within the Pollyanna Mineralized System.

Mineralization consists of pyrite, chalcopyrite, molybdenite, magnetite, bornite and cuprite. Associated alteration minerals are quartz, sericite, chlorite, epidote and carbonate. The Gibraltar deposits all show secondary oxidation and secondary enrichment with the formation of chalcocite as coatings and as replacement of pyrite and chalcopyrite.

Production figures indicate that silver and minor gold mineralization is associated with these orebodies (see Gibraltar East (093B 012) for figures). Total measured recoverable reserves in 1988 for all the orebodies were 183.24 million tonnes, grading 0.32 per cent copper and 0.009 per cent molybdenum (Placer Dome Inc., Annual Report 1988). As of December 31, 1992, mining reserves (proven and probable at cutoff of 0.20 per cent copper) of the Pollyanna were 33,112,250 tonnes of 0.322 per cent copper and about 0.008 per cent molybdenum. Mineral resources were 60,872,100 tonnes of 0.267 per cent copper and about 0.007 per cent molybdenum (CIM Special Volume 46, page 202).

Combined (proven and probable) reserves for Pollyanna are 47.7 million tonnes grading 0.300 per cent copper and 0.009 per cent molybdenum. Combined (proven and probable) leachable ore reserves of the Connector are 1.2 million tonnes, grading 0.372 per cent copper. Total mineable reserves in 1995 for all ore deposits are 179.0 million tonnes grading 0.297 per cent copper and 0.009 per cent molybdenum (Gibraltar Mines Limited, Annual Report 1995).

In 1994, drilling (23 holes, 3150 metres) focused on induced polarization targets on two zones: the Pollyanna-GM zone immediately east of the Pollyanna pit, and the Connector zone between the Pollyanna and Gib-east zones. In 1995, drilling (37 holes, 4961 metres) was carried out on the Pollyanna, GM and Connector zones.

The Pollyanna Mineralized System which trends in an east-southeast direction into the GM claims, contains three major mineralized zones. The first zone, Zone A, has been identified as a high level (i.e. near surface) zone that contains abundant pyrite. Zone A is distinct from the other zones as it is comprised of a steeply dipping (60-70 degrees northeast) system containing variable amounts of chalcopyrite and molybdenite. This steep structure results in a sharp contact between the mineralized material and the non-mineralized material to the north.

The second zone which occurs south of Zone A is Zone B. This zone which is a shallower dipping system (0-20 degrees northeast) contains a relatively high amount of pyrite but usually less than that of Zone A. The primary sulphide assemblage is pyrite-chalcopyrite-molybdenite. Typically, in both Zones A and B, the pyrite acts as near surface blanket grading into a pyrite-chalcopyrite rich assemblage as depth increases.

The southernmost and broadest zone in the Pollyanna Mineralized System is Zone C. It is characterized by a shallow dipping (10-40 degrees southwest) magnetite-bornite-chalcopyrite +/- pyrite-rich assemblage indicative of a low sulphide regime in relation to Zones A and B.

Drillholes have also confirmed the presence of a mineralized zone between the north end of the Gibraltar East Pit and the Pollyanna Pit. The mineralization occurs in Mine Phase Tonalite which appears to grade into Leucocratic Phase and Granite Mountain Phase Trondhjemite immediately south of the drillholes. The hostrock is variously altered with quartz, chlorite, sericite, epidote, carbonate and clay. A strong oxide zone was intersected by all drillholes and significant amounts of chrysocolla, malachite and limonite were observed. Although the oxidation is extensive it appears that very little leaching has occurred. Chalcopyrite and pyrite with minor amounts of chalcocite and molybdenite were observed below the oxide zone. All drillholes intersected ore grade mineralization of either leachable or millable material. The drilling supports the concept that a large barren core of trondhjemite, surrounded by mineralized tonalite, exists between the various Gibraltar mines pits.

Westmin expects to mine about 30,000 tonnes of ore from the Pollyanna pit in 1997, as part of its staged process of mining on the property (T. Schroeter, personal communication, 1997).

Drilling during 1997 on the Connector zone added approximately 49 million tonnes of mineable sulphide reserves, representing an additional 3.3 years of mine life. Also, approximately 15 million tonnes of oxide reserves were outlined above the Connector zone sulphide ore, and will extend the life of the SX-EW plant by 6 to 7 years.

In mid-January 1999, Boliden began to shut down the mine, with full closure by February 1999. In April 1999, Taseko Mines Limited announced that they will acquire the Gibraltar mine.

Pollyanna Reserves as of December 31, 1998 are:

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                                                      Cutoff
                          Ore(tonnes)   Cu(%)   Mo(%)  (%Cu)
Pollyanna       proven     31,101,205   0.317   0.010   0.20
                probable    1,793,777   0.285   0.008   0.20
                combined   32,894,982   0.315   0.010   0.20
PGEC            proven     39,758,018   0.271   0.010   0.16
(Pollyanna-Gib  probable    5,605,496   0.261   0.001   0.16
East Connector) combined   45,363,514   0.270   0.010   0.16
(Exploration in BC 1998, page A10; from Boliden Limited).
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A joint venutre between Gibraltar Mines Ltd. and Ledcor Mining Ltd. brought the Pollyanna pit back into production at a rate of 35,000 tonnes of ore per day in October 2004 (PR REL Oct.13, 2004). Gibraltar Mines Ltd. is controlled by Taseko Mines Ltd., which in turn is managed by Hunter Dickinson Inc. See Gibraltar East (093B 012) for the new reserve, resource, production figures and bibliography.

In 2019, an updated resource estimated was released for the Gibraltar mine with a measured and indicated resource of 1 109 000 000 tonnes grading 0.25 per cent copper and 0.007 per cent molybdenum and an inferred resource of 59 000 000 tonnes grading 0.21 per cent copper and 0.004 per cent molybdenum (Weymark, R. [2019-11-06]: Technical Report on the Mineral Reserve Update at the Gibraltar Mine, British Columbia, Canada).