Chalcopyrite in calcite skarn copper ore

Virtual Museum ID: 19-GM12

Specimen Summary


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. Chalcopyrite is an important copper ore mineral found in many different types of copper deposit. A characteristic deep brass yellow colour and iridescent green-to-purple weathering surfaces distinguish chalcopyrite from gold and sulphides such as pyrite. It is sometimes mistaken for Gold because of its bright yellow colour; however, it is harder, more common, and chalcopyrite commonly occurs with other copper sulphide minerals such as bornite and weathers to malachite and azurite.

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.

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.

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:

Greenwood Museum (GM)

Sub Collection:

-

Collection ID:

GM_12

Virtual Museum ID:

19-GM12

Accessibility:

Date Added to VM:

2019-06-06

Location Information

Sample Origin:

NE of Greenwood, BC

Specific Site:

Oro Denoro Mine

UTM Easting:

387019

UTM Northing:

5442630

Datum:

11 (NAD 83)

Coordinate Accuracy:

Approximate

Specimen Details

VM Category:

Ore Sample

Primary Features:

Chalcopyrite in calcite skarn copper ore

Primary Mineral Formula:

CuFeS 2, CaCO 3, {Ca2}{Al2Fe3+}

Primary Category:

sulphide carbonate

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:

Brooklyn Group

Geological Period:

Triassic

Stratigraphic Age:

201.3 to 252.17 Million Years

Geological Belt:

Omineca

Geological Terrane:

Quesnel

Minfile ID:

082ESE063

Site Details:

The Oro Denoro Mine is 10.2 kilometres northeast of Greenwood, at elevation 1066 metres on the divide between Eholt and Fisherman creeks. The property adjoins the Emma Mine (082ESE062) to the north. Access to these properties is about 0.6 kilometre southwest from Highway 3 by level gravel road along an old railway bed.

Production from Oro Denoro, in the period 1903 to 1917, totals 123,782 tonnes containing 116.5 kilograms of gold, 953.4 kilograms of silver, and 1690.6 tonnes of copper; this does not include several thousand tonnes of ore shipped to the Phoenix mill (082ESE020) in 1978.

The Oro Denoro mine is centrally located within a 2.4 kilometre long, north-south alignment of skarn deposits which includes the Emma and Jumbo (082ESE062) on the north and the Cyclops and Lancashire Lass (082ESE122) on the south. Mine development began at Oro Denoro in 1896 and by 1900 the underground workings consisted of a shaft 70 metres deep, and 240 metres of crosscuts and drifts. By 1908 an additional 40 metres of sinking and 20 metres of crosscutting was completed. The present mine workings cover an area of about four hectares in the central part of the claim.

In the early period of mining at the Oro Denoro mine, 1903 to 1910, ore was drawn from a number of large stopes on two underground levels and five open pits. The two southermost pits or quarries, Nos. 1 and 2, were the principal source of copper ore. These are interconnected and have a general east-west elongation. The trend of the excavations appears to follow the course of a number of large steeply dipping calcite lenses in the skarn by the granodiorite contact which is near the north wall. Quarry No. 3, centred about 60 metres north of Nos. 1 and 2, is the second largest pit. Here the mineralization was concentrated in a tongue of skarn projecting deep into the granodiorite mass. Quarries Nos. 4 and 5, centred about 45 metres northwest of No. 3, are relatively small. The magnetite rich ore was situated between a small remnant of limestone in the skarn and the granodiorite. Control of the mineralization appears to be east-west cross fractures trending approximately perpendicular to bedding in the limestone host rocks.

The most recent excavation, which is located immediately west and south of the old quarries, is an open pit, 150 metres long and 45 metres wide, developed mainly in garnetite skarn at the summit of Oro Denoro's 'Mine hill'. The target of these workings was a mineralized zone near the south end of the pit. The mine area is traversed by a number of ore controlling faults. The most significant is a pronounced shear that strikes 120 degrees from the north end of the main pit and through No. 1 quarry. Important movement on this zone has resulted in the emplacement of exotic formations in the skarn such as a wedge of carbonaceous schist in the main pit and epidotized volcanic breccia along the south wall of No. 1 quarry. Of less importance are two minor faults dipping 80 degrees east and 75 degrees southeast causing local displacements in the skarn-granodiorite contact.

Ore reserves at Oro Denoro comprise, in part, the sills and pillars in the old underground workings below the Granby pit. This mineralization is exposed in the lower adit level. More than several hundred thousand tonnes of ore grading in excess of 0.5 per cent copper may still remain in the mine according to old reports. Indicated resources were estimated at 1,058,700 tonnes of 0.95 per cent copper, 0.7 gram per tonne gold and 10.3 grams per tonne silver (Campbell, 1968 and Western Miner, October 1968). In 1967, W.J. Weymark estimated the following: reasonably assured, indicated and possible ore reserves at 42,460,000 tonnes grading 0.92 per cent copper, 0.82 grams per tonne gold, and 10.97 grams per tonne silver. This breaks down to 3,524,400 tonnes of reasonably assured ore grading 1.32 per cent copper, 0.82 grams per tonne gold, and 10.97 grams per tonne silver; 18,388,600 tonnes of indicated ore grading 0.80 per cent copper, 0.82 gram per tonne gold, and 10.97 grams per tonne silver; 6,331,200 tonnes of possible ore grading 0.75 per cent copper, 0.79 gram per tonne gold, and 10.97 grams per tonne silver; and 14,216,500 tonnes of possible ore, below the diorite sill, grading 1.07 per cent copper, and minor gold and silver. (Western Miner, February 1967, page 49.)

Exploration activity on the property and adjacent areas from 1950 to 1989 is summarized in Assessment Report 21329. See also History of Exploration and Development on National Mineral Inventory card 082E2 Cu4.

The area is underlain by limestone, sharpstone conglomerate, tuffs and breccias of the Triassic Brooklyn Group. These rocks are cut by granodiorite of the Jurassic-Cretaceous Wallace Creek Pluton and alkaline syenite of the Eocene Coryell Intrusions.

A skarn sample assayed 2.2 per cent copper, 6.0 grams per tonne, silver, and 0.15 grams per tonne gold (EMPR Paper 1989-3, Appendix 7). Another sample assayed 0.03 per cent cobalt (EMPR Bulletin 101, Appendix 4B).

Echo Bay Mines Ltd. drilled 5 holes totalling 250 metres in 1997.

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