Skarn with epidote crystal and calcite

Virtual Museum ID: 19-NCM06

Specimen Summary


Skarn is, rock(s) formed or altered by the interaction of magma, country rock, reactive fluids and heat are known as skarn.

Skarn or tactites are hard, coarse-grained metamorphic rocks that have been chemically altered by metasomatism(the chemical alteration of rock by hydrothermal and other fluids). Commonly forms around the edges of a magma body(or silicate rock) that intrudes into a carbonate layer composed of either dolomite or limestone. It consists mainly of Ca, Mg, Fe and/or Mn silicates which are free from or poor in water.

Epidote is a fairly common mineral that is usually pistachio green in colour. It occurs in metamorphic and igneous rocks and forms in many different geological environments. Although epidote can form long, slender, glassy prismatic crystals, it usually has a dull appearance where many very fine crystals grow together in a massive form, for example in veins or replacing other minerals. Epidote does not have any specific industrial uses and is not a source of particular elements or metals.

Calcite, a form of calcium carbonate, is a very common mineral found in many different geological settings. It is usually white, clear or very pale pink or yellow. It can look very similar to quartz but is easy to distinguish because it fizzes when it reacts with dilute hydrochloric acid. Calcite often occurs in veins or as fracture coatings or filling void spaces. Where crystals have enough time and space to fully form, calcite has a distinct rhombic shape. Calcite is the main mineral in limestone, marble and chalk, and is widely used in construction, agriculture and pharmaceutical industries.

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:

Chamber of Mines of Eastern BC (NCM)

Sub Collection:

-

Collection ID:

NCM_06

Virtual Museum ID:

19-NCM06

Accessibility:

Date Added to VM:

2019-06-11

Location Information

Sample Origin:

W of Nelson

Specific Site:

Queen Victoria Mine

UTM Easting:

467332

UTM Northing:

5482459

Datum:

11 (NAD 83)

Coordinate Accuracy:

Approximate

Specimen Details

VM Category:

Rock

Primary Features:

Skarn with epidote crystal and calcite

Primary Mineral Formula:

A2B3(SiO4)(Si2O7)O(OH) · CaCO₃

Primary Category:

silicate

Secondary Features:

Bornite, chalcopyrite, pyrite

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:

Ymir Group

Geological Period:

Lower Jurassic

Stratigraphic Age:

174.1 to 201.3 Million Years

Geological Belt:

Omineca

Geological Terrane:

Quesnel, Plutonic Rocks

Minfile ID:

082FSW082

Site Details:

The Queen Victoria mine is located about 11 kilometres west of Nelson. The deposit was discovered in 1890, production was first recorded in 1907 and continued sporadically until 1956.

The area is underlain by sediments of the Lower Jurassic Ymir Group, Jurassic diorite, meta-diorite and pyroxenite of unknown affinity (Unit Jp) and granodiorite of the Middle to Late Jurassic Nelson batholith (Open File 1991-16).

A zone of quartz-carbonate rich skarn, approximately 120 to 150 metres long by 30 metres wide and pinching to 3 metres at each end, strikes about 015 degrees with a 20 degree east dip. The skarn is hosted by limestone, dark grey quartzites and argillites of the Ymir Group at and near the contact with granodiorite.

The skarn is characterized by irregular bands of garnet, epidote and actinolite with minor disseminated, fine-grained magnetite and pyrrhotite alternating with bands of quartzite and schist. The bands vary from several centimetres to 15 metres or more in width and have been developed along strike for about 151 metres. Relatively thin layers of dark green amphibolite and blocky feldspar porphyry are observed in the footwall and blocky fine-grained greenish quartzites are in the hanging wall.

Mineralization consists of disseminated grains and irregular clusters of chalcopyrite and pyrite with minor bornite. The sulphide zones are highly irregular with no distinct boundaries. Folds in the hanging wall to the east of the zone have axes that plunge 10 degrees northeast. Small faults and feldspar porphyry dykes crosscut the skarn and host sediments.

Production totals 45,352 tonnes, recovering 7,651 grams of gold, 950,010 grams of silver and 672,630 kilograms of copper. The ore also contained traces of nickel and cobalt.

Work in 1966 delineated a second skarn about 0.8 kilometre west of the original open pit.

The original discovery was made here in 1890 and mining was carried on intermittently between that time and 1918. The workings were mainly open glory holes and these are still accessible.

Following the closing of the mine in 1918, little work was done on the property until 1955. In that year some diamond drilling was done. In the latter part of 1956 the Finley Company of Reno, Nevada, obtained an option. A few thousand tons of material was broken for mill feed but no regular mining program evolved.

In 1956, Swift Copper Mines Limited acquired 18 mining claims covering the property and in addition acquired a complete mill rated at 200 to 300 tons, located about 11.2 kilometres from the mining property.

Development in 1960 consisted of mapping, stripping, sampling, and other surface work, including a limited amount of Packsack drilling.

During 1961 a zone about 152 metres long was stripped by bulldozer and two old adits uncovered. In 1962 the Great West Mining Corporation Ltd. of Vancouver put down twelve diamond-drill holes, six in the vicinity of the workings, and six in a group about 610 metres west-southwest of the workings. Four holes of the latter group intersected a body of skarn about 12 metres thick mineralized with chalcopyrite and pyrite.

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