Gold (native) Quartz

Specimen Summary

Gold is a valuable, highly prized mineral used in everything from jewellery to electronics and dentistry. Gold is desirable due to its special properties, such as malleability and resistance to tarnishing. Gold is commonly microscopic or embedded within or around sulphide grains. Free visible gold occurs as disseminated grains, or rarely as crystals. Crystals of gold commonly form within or around quartz. In its natural mineral form, gold is commonly alloyed with silver. Gold is distinguishable by its characteristic golden yellow colour and extreme heaviness.

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.

This sample is from the Golden Contact mine, also known as the Anderson Lake mine, near McGillivray in BC, about 30 km west-southwest of Lillooet.

McGillivray, once known as McGillivray Falls, was a small mining town on the western shore of Anderson Lake. Gold was mined in the area during the Bridge River Gold Rush of the late 1800s. The historic Pioneer mine is 20 km to the northwest.

The town, nearby falls and mountain were named by an early miner, Jack McGillivary, and his brother, Don. The brothers owned MGillivray Bros, which helped build the PGE railway between Squamish and Lillooet, and had worked on the construction of the CPR main line through the Fraser Canyon. Some houses still remain from the early 1900s.

Mineralization in the area is contained in steeply dipping quartz veins 4-7 m wide with free gold and minor chalcopyrite (seen green-blue tarnished in this sample), pyrite, arsenopyrite, sphalerite and galena.

Several different companies owned this underground mine and constructed adits for exploration and sampling, but the mine was only in production from 1900 to 1904 and again in 1910 and in 1962.  In total, 9,177 tonnes or ore was extracted, producing 21.4 kilograms of gold.

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:

Association for Mineral Exploration (AME)

Sub Collection:

-

Collection ID:

AME-555

Virtual Museum ID:

19-AME555

Accessibility:

Date Added to VM:

2018-02-15

Location Information

Sample Origin:

McGillivary Creek, B.C.

Specific Site:

Golden Contact Mine (Anderson Lake Mines Ltd.)

UTM Easting:

539100

UTM Northing:

5608271

Datum:

10 (NAD 83)

Coordinate Accuracy:

Approximate

Specimen Details

VM Category:

Mineral

Primary Features:

Gold (native) Quartz

Primary Mineral Formula:

Au, SiO2

Primary Category:

native element oxide

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:

Bridge River Complex (Group)

Geological Period:

Mississippian to Jurassic

Stratigraphic Age:

251.9 to 323.2 Millions Years Ago

Geological Belt:

Coast Crystalline

Geological Terrane:

Bridge River

Minfile ID:

092JNE079

Minfile Link:

https://minfile.gov.bc.ca/Summary.aspx?minfilno=092JNE079

Site Details:

The Brett (Anderson Lake Mine) occurrence is located west of Anderson Lake and north of McGillivray Creek.

The occurrence is hosted in metasediments consisting of argillite, slate, tuffs and minor limestone of the Mississippian to Jurassic Bridge River Complex (Group), which is intruded by granodiorite tongues and stocks of the Cretaceous to Tertiary Bendor pluton. Slates are schistose and fissured in all directions. The fissures are frequently quartz filled.

The deposit consists of an irregular, ribboned quartz-ankerite vein, averaging 4 to 7 metres in width, striking north and dipping steeply west and conformable to the black slates and interbedded carbonaceous phyllite. Visible gold is concentrated locally and is occasionally coarse. Pyrite is the main sulphide in the vein, with some intersections showing arsenopyrite, chalcopyrite, sphalerite and sparse galena. Alteration minerals include sericite, mariposite, calcite and ankerite.

Due to the characteristically high amount of coarse free gold in the ore, additional cuts of the same crushed sample gave assay results that varied widely. A 2.4-metre channel sample (Sample 1815) assayed four times gave: 1145 grams per tonne gold and 528 grams per tonne silver, 5.8 grams per tonne gold and trace silver, 293 grams per tonne gold and 65.14 grams per tonne silver and 2.06 grams per tonne gold and 3.42 grams per tonne silver (Minister of Mines Annual Report 1962, page 27).

In 1910, a sample from the No.2 drift is reported to have assayed 166.9 grams per tonne gold over 35 centimetres (Assessment Report 11749). Sampling of the No.3 drift, in 1933, is reported to have yielded 8.5 grams per tonne gold over an average width of 1.5 metres, from 112 samples (Assessment Report 11749). The following year, assay plans from the No.2 and 3 levels reported values up to 26.7 grams per tonne gold over 2.58 metres (Assessment Report 11749). In 1947, sampling of the Mac tunnel is reported to have yielded a weighted average of 7.2 grams per tonne gold across 1.8 metres and for a length of 15 metres (Assessment Report 11749).

In 1983, a 10-metre sample of footwall material from the No.3 adit assayed 0.82 grams per tonne gold (Assessment Report 11749). In 2005, a dump sample assayed 1.15 grams per tonne gold (Assessment Report 28240).

The mine was in production from 1900 to 1904, in 1910 and again in 1962. The total amount of ore extracted was 9177 tonnes, which yielded 21.4 kilograms of gold. The mine was worked on several levels but most of the production came from the "49er" level.

Following the discovery of gold in the Bridge River area in 1896, and during the subsequent gold rush of the 1930s, the Anderson Lake area saw extensive exploration. The Anderson Lake mine was originally staked in 1897. During 1900 through 1903, Anderson Lake Mining and Milling completed three drifts following a quartz vein 1.8 to 2.4 metres in width. The No.1 drift, at 990 metres in elevation, extended for 45 metres, while the No.2 drift, at an elevation of 1035 metres, was 150 metres long. The No.3 drift also extended for 45 metres. In 1947, Golden Contact Mines acquired the property and completed 328.5 metres of diamond drilling and 88.5 metres of drifting in the “Mac” tunnel, located 26.5 metres below the No.3 drift. The following year the “49er” adit, located at an elevation of 956 metres, was driven for a length of 114.6 metres. In 1949, a further 151 metres of drifting and 76.8 metres of crosscutting was completed on the “49er” adit, while another adit known as the “Pep” adit, located 81 metres below the “49er” adit, was started with 18 metres of crosscutting. During 1950 through 1953, 639 metres of drifting, raises and crosscutting was completed on the “Pep” adit. In 1961, the “Pep” and “49er” adits were re-opened and a raise was driven between the two adits.

In 1983, X-Cal Resources completed a program of rock and silt sampling and geological mapping on the area as the Mac and X-Cal claims. In 1984, Magnus Resources completed a ground magnetic and electromagnetic survey on the area. In 1985, Hudson Bay Exploration and Development completed a program of geochemical sampling, geological mapping and a ground electromagnetic survey. The following year, Magnus Resources completed a lone drill hole, totalling 36 metres. In 1989 and 1990, Teck completed programs of rock, silt and soil sampling, geological mapping and a ground electromagnetic survey on the area. In 1991, Cogema completed a program of geochemical sampling and geological mapping on the area. In 2005, a minor prospecting program was completed. In 2006 and 2007, the area immediately south west was prospected as the Lil Andy claims. In 2012, a minor program of soil sampling was completed.

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