Quartz-sulphide vein

Virtual Museum ID: 19-D9-05

Specimen Summary


vuggy, white to orange quartz with 25% galena and minor dark brown sph and cpy

Quartz is the second most abundant mineral on Earth, occurring in many different types of rocks. Although usually clear or milky white in colour, quartz can be found in a variety of colours because of impurities in the crystal structure. Pure quartz is made up of silicon and oxygen only, but atoms of other elements, like iron or titanium, often make their way into the quartz crystal structure. Some varieties of quartz, like purple amethyst, are considered to be semi-precious gemstones and have been used since ancient times to make jewellery and decorative objects.

Galena is the main ore mineral for lead. Because of its relatively low melting temperature, it can be easily smelted and has been used as a source of lead since ancient times. Galena has a cubic crystal system and can often be found as cubes or octahedra. Its shiny grey metallic lustre and heavy, dense nature make it easy to recognize. Galena often contains small amounts of silver, which add to its economic value.

Sphalerite is the main ore mineral for Zinc, and although relatively common, finding it in commercial amounts is somewhat rarer. The zinc will give the mineral a yellow or red hue, but iron can replace the zinc in the atomic structure, making the crystals black. Rarely, cobalt finds its way into the structure, and produces green crystals.
Pyrite is a common iron sulphide mineral found in many different geological settings. It has a brassy-yellow metallic colour that has caused many people to mistake it for gold, giving it the name “Fool’s gold”. Pyrite and gold can be quite easily distinguished from one another: pyrite is less yellow and much lighter and harder than gold, which can be scratched with a pocket knife. Pyrite often forms perfect cubes, which can grow to quite large sizes, because of its crystal structure. The word pyrite comes from the Greek word ‘pyr’ meaning fire, because it will spark if hit with other metal or stone objects.

Specimen Data

 

The information listed below relates to the current holding location or collection that the sample is from, and whether the item is viewable at that location or is part of a private collection. Coordinates are given as guides, and we remind you that collecting specimens from these locations is not allowed. Caution is advised visiting such sites and Below BC assumes no responsibility for any injuries or trespassing charges that may occur as a result of the viewer entering these sites.

Collection Details

Original Collection:

Smithers Exploration Group (SEG)

Sub Collection:

Stewart-Iskut deposits

Collection ID:

D9-05

Virtual Museum ID:

19-D9-05

Accessibility:

Date Added to VM:

2019-02-21

Location Information

Sample Origin:

Stewart, BC

Specific Site:

Prosperity/Porter Idaho

UTM Easting:

442077

UTM Northing:

6195523

Datum:

09 (NAD 83)

Coordinate Accuracy:

Specimen Details

VM Category:

Mineral

Primary Features:

Quartz-sulphide vein

Primary Mineral Formula:

SiO2 · S^2-

Primary Category:

sulphide

Secondary Features:

Advanced Geological Information

 

The following section provides geological data relating to the specimen or the site it was collected from, when available. Information has been obtained from various sources including private and government datasets but may not be up to date. Any geological time periods or ages listed often relate to the primary geology of the area, and may not be the actual date of an event such as mineral formation.

Geological Formation:

Betty Creek Formation (Hazelton Group)

Geological Period:

Lower Jurassic

Stratigraphic Age:

Tertiary

Geological Belt:

Coast Crystalline

Geological Terrane:

Stikine

Minfile ID:

103P 089

Site Details:

The Prosperity and Porter Idaho mines are located on the south slope of Mount Rainey, 5.5 kilometres southeast of Stewart. These two mines were in operation between 1922 and 1950. The deposit is hosted in andesitic to felsic volcanics of the Lower Jurassic Betty Creek Formation (Hazelton Group), which are intruded to the west and north by Eocene granodiorite of the Hyder pluton (Coast Plutonic Complex). These are overlain to the east by clastic sediments of the Middle-Upper Jurassic Salmon River Formation (Hazelton Group).

Mineralization is contained within dacitic crystal to welded tuffs with minor andesitic lapilli tuff and dacitic waterlain tuff within a thick sequence of epiclastic conglomerate, andesitic and dacitic ash tuff, lapilli tuff, crystal tuff, welded tuff and tuff breccia.

The Prosperity and Porter Idaho deposit comprises six major subparallel shear zones, spaced roughly 150 to 175 metres apart, striking 160 to 180 degrees and dipping 45 to 65 degrees west. These occur in volcanics that strike 020 to 040 degrees, and dip steeply west. The shear zones have been traced on surface for between 200 metres (Prosperity West vein) and 1000 metres (D vein) and downdip for a vertical distance of up to 425 metres (D vein). Widths vary from between 2 and 13 metres. The shear zones terminate to the south against the Big Rig fault which strikes approximately 084 degrees and dips 50 degrees north. In the vicinity of the fault, the shears are dragged westward with reduced dips of 40 degrees. The shear zones show some minor lateral displacement by other west striking faults and are cut by several lamprophyre dikes.

The shear zones contain discontinuous, well mineralized lenses and shoots up to 13 metres wide, 250 metres long and at least 200 metres downdip. High-grade mineralization occurs as individual sinuous massive sulphide veins usually between 0.2 and 0.6 metre wide and sometimes coalescing into veins up to 2 metres wide. The veins typically follow the footwall and hangingwall of the shear zones within sheared, altered and mineralized wallrock. Mineralization consists of galena, sphalerite, pyrite, tetrahedrite and minor chalcopyrite, pyrrhotite, argentite, pyrargyrite, polybasite, native silver, arsenopyrite and trace electrum. Adjacent to the veins, disseminations, blebs and veinlets of quartz, ankeritic carbonate, manganese oxide and similar sulphides occur in variably silicified country rock for up to 5 to 6 metres outward from the veins.

In 1989, underground geological reserves were 826,400 tonnes grading 668.5 grams per tonne silver, 5 per cent lead and 5 per cent zinc (D. Alldrick, Ph.D. Thesis, University of British Columbia, 1991).

Between 1922 and 1950, 27,268 tonnes of ore were periodically mined from the underground workings of the Prosperity and Porter Idaho mines. The production came from the D, Prosperity and Blind veins, and averaged 0.986 gram per tonne gold, 2692.1 grams per tonne silver, 5.08 per cent lead, 3.853 per cent zinc and 0.101 per cent copper. Sorted ore was shipped via an aerial tramway to tidewater and barged from there to the smelter at Tacoma, Washington. The mine workings cover a vertical interval from 1287 to 1707 metres. Most of the underground workings are located on Lot 4730 (Nettie L.), Lot 1858 (Prosperity), Lot 1857 (Tea Pot Dome), Lot 1866 (Gargoyle Fraction), Lot 4731 (Sunday), Lot 4729 (Lucille) and Lot 4737 (Prickly Heat Fraction).

Apart from sporadic examinations between 1947 and 1970, little definitive work had been performed since mine closure. In 1975, Seaforth Mines Ltd. drilled three holes to test the vertical extension of one ore shoot with mixed results. In 1980-81, Pacific Cassiar Limited commenced a program of rehabilitation to permit evaluation of the vein systems in light of re-interpretation of old data, and enhanced silver prices. During 1982, Pacific Cassiar Limited carried out a program of reconnaissance and detailed geological mapping including limited trenching, and rock and soil sampling.

In 2016, Skeena Resources announced plans to acquire private company Mount Rainey Silver for its Porter Idaho silver property. The 5.9 square kilometre property hosts two shear hosted and silver-rich vein systems named the Silverado (103P 088) and Prosperity-Porter Idaho. Both showings are spaced 2 kilometres apart, located on opposite sides of a mountain that overlooks the town of Stewart.

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