The Hecla occurrence is located on the southwest flank of Idaho Peak at about 1219 metres elevation. Silverton, British Columbia is located 2.75 kilometres to the west.
The Surprise Crown grant (Lot 563) covers the ground hosting the Hecla occurrence. This should not be confused with the Hecla Reverted Crown grant (Lot 13576) or the Hecla ore zone on the Mammoth No. 7 level (082FNW060).
In 1961, Loma Minerals Ltd. held a lease that included the Hecla, Standard (082FNW180), Mammoth (082FNW060), Monarch and Enterprise (082FNW148) groups. Property title was transferred to Johnsby Mines Ltd. in the following year and an extensive development program was commenced on the hangingwall branch of the Standard-Mammoth lode system. This branch follows a general eastern course to the Mammoth mine which lies about two kilometres to the east. The Hecla ore zone lies along this lode between the Standard and Mammoth occurrences. Work on the Hecla occurrence was confined to the Hecla drift, with a total length of 1006 metres, following the trend of the lode. An additional 293 metres of crosscutting and 76 metres of raising was done. Three new ore shoots were discovered during a diamond drilling program, totalling 1452 metres, in the newly collared adit on the north-neighbouring Surprise claim. Stopes were started at about 231, 427 and 518 metres east of the portal crosscut. Production continued until 1966 when the new ore was exhausted. Panoil Canadian Minerals Associates optioned the property in 1967 with further development work on the Mammoth occurrence. Arjan Pacific Ltd. acquired ownership of 32 Crown grants in 1973 which included claims covering the Standard, Hecla and Mammoth lodes. Mengler Leasing Co. operated the property in the early 1980s.
The Hecla occurrence is hosted by siliceous, carbonaceous and locally calcareous argillite, minor quartzite and limestone of the Triassic Slocan Group. These are intruded by a granodiorite stock and various quartz porphyry and biotite hornblende porphyry dikes. The dikes are highly altered to quartz, calcite and sericite, close to the Standard veins. The structure of these strata is extremely complex owing to intricate folding and faulting.
Ore shoots discovered at the Hecla occurrence in 1964 ranged from 30 to 46 metres length. The shoots are along the westward projection of the Mammoth and Hecla zones.
No information could be found regarding the nature of the Hecla lode. Its proximity to the Standard lode along the Standard-Mammoth lode system suggest the types and style of mineralization are similar. Therefore a description of the Standard occurrence is given. The Standard lode-fissure consists of a wide, up to 50 metres, shear zone. Underground, the lode has been followed for nearly 2.39 kilometres. While the lode is somewhat sinuous, it strikes about 065 degrees and dips 20 to 80 degrees, averaging 45 degrees. Near the main orebody the lode has a maximum width of 46 metres. The zone has many small offsets and split in north-northeast and east-northeast branches at its eastern extremity. This is where the main orebody was found. The main ore shoot, known as the Big or Million Dollar stope, extends 366 metres vertically downward from the No. 3 level to below the No. 6 level. Other orebodies, which include the I vein, 640 vein, 620 vein and Spur vein, are scattered along the structure. The ore shoots are generally at angle to the main footwall shear and a sigmoidal shape is reported for some of them, joining the footwall and hangingwall of the structure.
The orebodies occurred generally close to the footwall of the structure and consisted of up to 4 metres of massive, sheared and coarse-grained galena or up to 3 metres of massive galena and sphalerite in veins, stringers and lenses. Breccia composed of argillite, quartzite and porphyry are common in the footwall of the structure. Other reported minerals include varying minor amounts of pyrite, chalcopyrite, tetrahedrite and rare pyrargyrite. The Big ore shoot consisted primarily of relatively clean galena. Ore mined in later years contained mixed sphalerite and galena with the former predominating. Quartz, calcite and siderite comprise the gangue mineralogy.
The controlling factors on mineralization are thought to be the extent of shearing, brecciation and faulting of hostrocks with the presence of porphyry playing a minor role.
Production records for the Hecla occurrence indicate 20,108 tonnes of ore was mined between 1964 and 1983. This yielded 7,301,796 grams silver, 456 grams gold, 911,872 kilograms zinc, 647,478 kilograms lead, 5578 kilograms cadmium and 390 kilograms copper.
