Virtual Museum ID: 17-PME22746
Specimens from the Rock Candy Mine
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 of quartz is from the Rock Candy mine about 27 km north of Grand Forks, BC. The mine is known for several impressive specimens of quartz, fluorite and barite that were found there.
The sample is a good example of a kind of quartz called ‘drusy’ quartz on pale green fluorite. Drusy quartz is made up of thousands of tiny individual quartz crystals that coat a rock surface, often filling a cavity, giving the surface a sparkling look.
Early prospectors mistook the Rock Candy mine’s green fluorite for copper mineralization, which is also often green at the Earth’s surface. They staked the ground the mine is on in 1916 but were soon disappointed when they realized they hadn’t actually found a copper deposit. The Consolidated Mining and Smelting Co. of Canada Ltd took over the claims in 1918 and operated the mine intermittently up until 1942. During that time, 36,760 tonnes of fluorite and 1,700 tonnes silica were produced.
Today visitors can pay to collect their own samples from the site.
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.
Original Collection:Pacific Museum of Earth (PME)
Virtual Museum ID:17-PME22746
Date Added to VM:2017-12-08
Sample Origin:Grand Forks, British Columbia
Specific Site:Rock Candy Mine
Datum:11 (NAD 83)
Primary Mineral Formula:SiO2
Primary Category:oxide silicate
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:Penticton Group
Stratigraphic Age:56 - 33.9 Ma
The Rock Candy fluorspar property is located on Kennedy Creek, approximately 27 kilometres north of Grand Forks. The main showing is exposed between 790 and 880 metres elevation on the wooded slopes north of Kennedy Creek. It can be reached by forest access road which branches off the North Fork road approximately 19 kilometres north of Grand Forks, follows Pass Creek westerly for 3.5 kilometres and then follows Rock Candy Creek north for approximately 8.5 kilometres to Kennedy Creek.
The deposit was discovered in 1916 by two prospectors who mistook the green fluorite for copper mineralization. Once the true nature of the deposit was realized the property was acquired by Consolidated Mining and Smelting Company of Canada Ltd. and immediately put into production. It was in operation intermittently between 1918 and 1942 and a total of 56,000 tonnes of ore, with an average grade of 68 per cent CaF2 and 22 per cent SiO2, produced about 36,759,501 kilograms of fluorite and 1,673,000 kilograms of silica. The mine operated through two adits; all mining was carried out using shrinkage stope methods. The ore was transported by aerial tramway to the Granby River valley, approximately 4 kilometres east of the mine site, and from there to the Trail smelter where most of it was used. The adits remained open until the 1980's at which time they were blasted closed. It is estimated that approximately 12,300 tonnes of broken ore remain in the stopes and that 47,800 tonnes of probable ore remain in pillars and sills in and adjacent to stoped areas. The mine was controlled by Cominco until its recent acquisition by a mineral collector.
The region in the vicinity Kennedy Creek, west of the Granby River, is underlain by andesites, dacites and trachytes of the Eocene Penticton Group, Marron Formation, which are intruded by syenite and monzonite of the Eocene Coryell plutonic suite. The Coryell intrusions may be the plutonic equivalent of the Marron Formation.
The Rock Candy fluorspar deposit consists of an intricate network of subparallel veins, which vary from a few centimetres to approximately 10 metres in width. They occupy a silicified, northerly-trending, moderate to steeply west-dipping fracture zone in Tertiary andesitic volcanics adjacent to a large syenite intrusion with offshoot dikes. Within the mine the veins were numerous and closely spaced. The developed mineralized zone extends 200 metres north from Kennedy Creek and has a maximum width of 15 metres. The vein is exposed again about one kilometre north of the main developed zone.
The andesites that host the fluorite veins are predominantly fine to medium grained, greenish to grey in colour and contain albite, oligoclase and actinolite with minor magnetite and biotite. Quartz occurs as veinlets and cavity fillings. Sericite, calcite and chlorite are alteration minerals. Immediately adjacent to the veins, the andesites, which are thought to be early Tertiary age, are strongly altered, weathered to a pinkish buff colour and contain chlorite, sericite, quartz, calcite, pyrite and abundant clay minerals including kaolin. The outcrops east of the vein system are medium to coarse-grained, massive pink Coryell syenite. The Coryell intrusion contains large pink and green feldspar crystals, predominantly orthoclase, and a minor amount of plagioclase. The centres of some of the orthoclase crystals have been identified as hyalophane, a barium- rich orthoclase. Biotite, hornblende, augite, magnetite and traces of quartz, apatite, sphene and zircon are accessory minerals in the syenite. The ferromagnesian minerals are commonly altered to chlorite and epidote is locally present. The numerous dikes in the area related to the Coryell intrusion consist of altered feldspars with some interstitial quartz and secondary calcite and chlorite. Fluorite has been reported from one such dike. Granite and granodiorite correlative with the Nelson batholith (Jurassic-Cretaceous) occur south of Kennedy Creek.
Excellent surface exposures of a large vein exist near the old workings, the eastern margin of which is covered with glacial till. The vein is 3 to 4 metres wide and consists mostly of massive fluorite, bounded on the west by 1.5 to 2 metres of fluorite-matrix breccia and a thin composite banded margin adjacent to altered country rocks. The massive part of the vein is coarse grained, apple to emerald green fluorite and some pale purple fluorite cut by numerous vuggy quartz veins. Within the mine, numerous large vugs have been reported which are locally in excess of one metre in width and filled with white kaolin or lined with crystals of barite, quartz, calcite and fluorite. The marginal breccia contains altered subangular fragments of volcanic country rocks in a matrix of purple and green fluorite, chalcedony, kaolin, pyrite, quartz and calcite. The banded western margin of the vein comprises both crystalline and massive, barite with calcite, fluorite, chalcedony and quartz. Chalcopyrite, galena, chalcocite and covellite have been reported by previous investigator but these minerals are no longer exposed. Numerous fluorite veinlets, 4 to 5 centimetres thick and subparallel to the main vein, cut the altered volcanic rocks.
Fluorite mineralization is exposed again one kilometre north of the mine. In this area a 1-metre-wide vein cuts the altered volcanic rocks. It consists of massive pale purple, and pale green fluorite intruded by younger quartz veins and a breccia a few centimetres across consisting of angular fluorite fragments in a matrix of small quartz crystals. Small vugs lined with quartz crystals are abundant. A strong fault lineament connects this showing with the main workings and projects some distance to the north and south. Drilling shows intermittent development of fluorite mineralization along this fault but no economic grades have been reported except from the main workings.