Quartz-sulphide ore vein

Virtual Museum ID: 19-D13-09

Specimen Summary


sulphides are pyrite, chalcopyrite, 5% tetrahedrite(?) in order of abundance; quartz gangue

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.

Chalcopyrite is the most common ore mineral for copper and is a sulphide of iron and copper. Chalco comes from the Greek word chalko, meaning copper. Chalcopyrite is commonly found in sulphide deposits in most ore-forming environments. A characteristic deep brass yellow colour and iridescent green-to-purple weathering surfaces distinguish chalcopyrite from gold and sulphides such as pyrite.

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.

Tetrahedrite is an important ore mineral for the elements copper, and antimony. It forms commonly with tennantite and the amount of each mineral produced depends on the chemistry of the original fluid mixture. While copper is common and has many applications for every day use, the antimony found within tetrahedrite is much rarer and special. The largest producer of the antimony in the world is China, with one major mine called Xikuangshan Mine responsible for most of this production. Antimony is used as an alloy with lead in older lead acid batteries, and in alloys with tin. It is an uncommon element; however, it is included in over a hundred known minerals.

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:

Dome MTn

Collection ID:

D13-09

Virtual Museum ID:

19-D13-09

Accessibility:

Date Added to VM:

2019-08-21

Location Information

Sample Origin:

-

Specific Site:

Dome Moutain

UTM Easting:

653141

UTM Northing:

6068487

Datum:

09 (NAD 83)

Coordinate Accuracy:

Specimen Details

VM Category:

Ore Sample

Primary Features:

Quartz-sulphide ore 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:

Nilkitkwa Formation (Hazelton Group)

Geological Period:

Lower-Middle Jurassic

Stratigraphic Age:

Jurassic

Geological Belt:

Intermontane

Geological Terrane:

Stikine

Minfile ID:

093L 022

Site Details:


At the Dome Mountain (Forks) occurrence, the original showing was in the creek bed, in a northeast trending shear zone in schistose andesites of the Lower-Middle Jurassic Nilkitkwa Formation (Hazelton Group).

The Forks consists of two veins that are found to be striking west south/west and dipping at a shallow angle towards the Boulder structure. The Forks Gold Deposit is a flat lying, extremely sheared and altered quartz breccia vein structure with a thickness of up to 12 metres. Drilling in 1987 intersected intervals up to 7.6 metres grading 10.42 grams per tonne gold and 53.38 grams per tonne silver (as reported in Assessment Report Assessment Report 28891).

The orebody (10 by 30 metres long) was reported as quartz heavily charged (5 to 10 per cent) with galena, arsenopyrite, pyrite and sphalerite. Later tunnelling outlined two quartz veins averaging 30 to 150 centimetres in width hosted in sericite-carbonate-fuchsite altered and foliated tuffs. The veins contain pyrite, galena, sphalerite and arsenopyrite. One vein, trending northwest and dipping northeast averages (weighted) 42.1 grams per tonne gold and 85.4 grams per tonne silver over 12 metres. The other vein trends northeast and averages 15.3 grams per tonne gold and 59.0 grams per tonne silver.

Prospectors first staked claims on Dome Mountain in 1914 to cover several showings of gold-bearing quartz veins. In 1923, three shafts, totalling 225 metres of underground drifting were completed on the property by Dome Mountain Mining Company. The next year, all work was halted due to the patchy nature of the gold mineralization and excessive water in the workings.

Noranda Exploration Corporation Limited consolidated all the claims on Dome Mountain in 1984 and conducted a program of soil geochemistry surveys, geological mapping, trenching and 33 diamond-drill holes. Canadian-United took over the operation in 1985 and proceeded with a diamond drilling program.

In 1989, Teeshin Resources Limited reported mineable reserves of 18120 tonnes at 23.67 grams per tonne gold from a shallowly dipping vein in the Forks zone (Property File Placer Dome Smit., 1990).

Drilling in 1985 defined a geological reserve of 20,000 tonnes grading 23.6 grams per tonne gold (Fieldwork 1986, page 212).

WORK HISTORY

Production is given for 1940 and 1951 totalling 5 tonnes but historic records do indicated work being done on Dome Mountain at that time.

In the early 1920s, on the Forks showing a shaft was sunk to 32.6 metres, a crosscut was driven to the vein on the 30 metre level, and "several hundred feet" of drifting carried out.

Work in 1985, with Noranda as operator, included trenching, and 1564 metres of diamond drilling in 33 holes on the Forks showing (093L 022); this work indicated 91,000 tonnes at 19.2 grams per tonne gold (George Cross News Letter, 1985, No. 240). However Assessment Report 28891 gives the following statement, "From 1985 to 1987 a total of 23 diamond drill holes on the Forks Gold deposit outlined a resource of 20,000 tonnes at a grade of 23.6 grams per tonne gold." The resource values in this paragraph appear to be at odds.

In 2008, Eagle Peak Resources collected soil sampling over a grid that covered Dome Mountain (Boulder) (093L 276), Forks (093L 022) and 9800 (093L 277). An IP survey was conducted over 22 kilometres and ground magnetic survey over 23.1 kilometres.

Refer to Dome Mountain (Boulder vein) (093L 276) for related details and a complete Dome Mountain property work history.

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