Molybdenite Galena Pyrite Quartz Vein
Virtual Museum ID: 19-BCGS-MX1
Soft silvery-grey molybdenite is the main ore mineral for molybdenum. Molybdenum, often just called ‘moly’, is used to make alloys with other metals like iron. Adding molybdenum to steel makes it stronger, harder and more resistant to corrosion. It also has a very high melting temperature, so is very useful when added to alloys to make aircraft parts and industrial motors, which need to withstand high temperatures.
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 its other 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.
Galena is the main ore mineral for lead. Because of its relatively low melting temperature, it can be easily smelted and has been used as a source of lead since ancient times. Galena has a cubic crystal system and can often be found as cubes or octahedra. Its shiny grey metallic lustre and heavy, dense nature make it easy to recognize. Galena often contains small amounts of silver, which add to its economic value.
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:British Columbia Geological Survey (BCGS)
Virtual Museum ID:19-BCGS-MX1
Date Added to VM:2019-05-07
Sample Origin:60km SE of Revelstoke, B.C.
Specific Site:Trout Lake Deposit
Datum:11 (NAD 83)
VM Category:Ore Sample
Primary Features:Molybdenite Galena Pyrite Quartz Vein
Primary Mineral Formula:MoS2 · PbS · FeS2
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:Lardeau Group
Geological Period:Lower Cambrian and younger
Stratigraphic Age:510 to 541 Ma
Geological Terrane:Kootenay, Slide Mountain
The Trout Lake deposit is located 60 kilometres southeast of Revelstoke on the northern spur of Trout Mountain between 1450 to 1520 metres elevation. Location of portal entrance is about 1200 metres northeast of the deposit. Access to the property is by logging road, five kilometres west of the north end of Trout Lake. The deposit lies near the old workings of the Lucky Boy (082KNW003) and Copper Chief (082KNW004).
Although molybdenum mineralization was first reported in 1917, much of the historical exploration of the area was related to the search for silver, lead, zinc and tungsten. Past work in the adjacent Lucky Boy and Copper Chief comprised underground development which resulted in ore shipments, primarily between 1901 and 1917.
Lower Cambrian and younger Lardeau Group metasedimentary and sedimentary rocks form a northwest trending broad belt northeast of the Kuskanax batholith. This belt, in part, straddles the northern end of the Kootenay Arc.
The Trout Lake deposit area is underlain by schists, phyllites and quartzites, with minor greenstone, of the Lardeau Group which are intruded by the Late Cretaceous "Trout Lake" stock. The metasediments have been tightly folded and strongly sheared in northwest trending folds which are broken into panels by northwest and north trending faults. Unconformably overlying these rocks are conglomerate, limestone and sandstone of the Upper Mississippian to Pennsylvanian or Permian Milford Group. The Middle Jurassic Kuskanax batholith, an aegirine-augite-bearing leuco quartz monzonite, lies 5 kilometres to the south of the property. Also within the region are a series of calc-alkaline stocks of Jurassic to Cretaceous age that includes the Trout Lake stock, which has been dated by potassium- argon methods on biotite at 76 Ma (Canadian Institute of Mining and Metallurgy January 1983). Molybdenum mineralization is associated with the Trout Lake stock.
The Lardeau Group includes light grey to black aphanitic argillites, very fine-grained grey to tan phyllites, and green to brown biotite-chlorite-sericite schists with prominent segregated quartz layers or lenses. Quartzite units are medium to coarse grained and impure, occurring in lensoidal beds; a carbonate unit is composed of massive to banded grey to white limestone and dolostone with variable skarn development. Milford Group rocks unconformably overlie the Lardeau Group and consist of a basal conglomerate overlain by shale, siltstone, phyllite and schist interlayered with sandstone, quartzite and limestone units.
The schistosity of the Lardeau rocks follows a regional northwest trend, dipping steeply northeast. First phase folding, recognized only locally, has been largely obliterated by a second phase. The dominant second phase fold axes trend northwest, with nearly horizontal to undulating moderate plunges. Folding as outlined by carbonate horizons varies from tight and isoclinal in the Lardeau Group to more open in the Milford Group rocks.
Regional metamorphic grade in the phyllite and schists of the Lardeau Group increases from north to south on the property, with chlorite, biotite and finally garnet/oligoclase appearing as the Kuskanax batholith is approached. There is a suggestion of an underlying arm of the batholith along an anticlinal axis, with intrusive apophyses manifesting themselves as dikes at surface. Superimposed on this regional metamorphic gradient is a thermal biotite hornfels surrounding the Trout Lake stock.
The intrusive rocks of the Trout Lake stock vary from quartz porphyritic granodiorite to quartz diorite porphyry as a network of intersecting dikes and irregular masses at surface which coalesce downward into a large stock. There appears to be as many as four distinct intrusive phases, with the earliest porphyritic granodiorite making up the bulk of the stock, followed by aplite dyking, and being cut successively by a quartz diorite porphyry set of dykes, an intermediate dike set of granodiorite composition and finally a later quartz diorite set. The dikes are inter-mineral, as they both cut off and are cut by mineralized quartz veins.
A dominant feature is strong north and northwest faulting, which separates the country rock into "panels". The strong north trending "Z" fault appears to have exerted a control on the location of the Trout Lake stock and subsequent mineralization, as well as showing post-mineral movement. Many small conjugate and splay faults cut the Trout Lake deposit underground, but displacements on these faults are generally less than 10 metres.
Dike and quartz vein orientations also show interesting conjugate patterns, with prominent northeast and northwest sets as well as north-south sets, and lesser flat dipping veins. In general, both the dikes and veins appear to fill northwesterly b-c and northeasterly a-c joints, with the latter being more dilational and therefore often better mineralized. Veining increases toward several centres associated with intrusive apophyses, as north and northwest trending vein sets are developed in addition to the more widespread northeast trending set. Flat dipping veins also become more prevalent along with randomly oriented veins to form a true stockwork (Canadian Institute of Mining and Metallurgy January 1983).
Hydrothermal alteration at the Trout Lake deposit, as defined by quantitative X-ray diffraction studies on composite core sections, is composed of a central quartz-potassium feldspar-albite-minor biotite (potassic) zone coincident with molybdenum mineralization, which is overlapped by a slightly later, antipathetic quartz-sericite-pyrite (sericitic (phyllic)) zone. Ankeritic carbonate and chlorite are also common alteration minerals. In detail, many local fluctuations, reversals and retrograde minerals are observed. The relationships of biotite, sericite and chlorite are very complex due to the presence of a) regional metamorphic sericite, chlorite and biotite; b) thermal (hornfels) biotite development around the stock, on which has been superimposed c) hydrothermal sericite and biotite, both related to vein margins, and d) retrograde chlorite as the system cooled.
It appears that the sericitic alteration at Trout Lake was later than the potassic alteration which accompanied molybdenum mineralization (Canadian Institute of Mining and Metallurgy January 1983).
Concentrations of iron, expressed as Fe2O3, suggest a distribution peripheral to the main molybdenum zone which may represent an iron sulphide halo of pyrrhotite related to the thermal biotite hornfels and/or pyrite related to the phyllic zone of hydrothermal alteration.
Molybdenite mineralization occurs over a vertical range of more than 1000 metres in two zones: the upper, smaller A zone, and the larger, irregular, vertically attenuated B zone, which is up to 300 metres long by 200 metres wide as defined by the 0.10 per cent MoS2 contour. Drill indicated reserves are 48,700,000 tonnes grading (0.193 per cent MoS2) at a 0.10 per cent MoS2. This includes 11,700,000 tonnes grading 0.195 per cent molybdenum (0.362 per cent MoS2) at a 0.20 per cent MoS2 cutoff (CIM Bulletin, January 1983, page 115 and Special Volume 46, page 780).
Molybdenite, as fine to medium flakes and rosettes accompanied by pyrite and pyrrhotite, is mainly present along the margins of veins in a well developed quartz stockwork. Occasionally, in higher grade zones (in excess of 1 per cent MoS2), the molybdenite is strongly disseminated in microfractured intrusive bodies up to 20 metres wide by 200 metres long, accompanied by large (over 10 centimetres) quartz veins and intense quartz flooding. The quartz vein stockwork is best developed in and around the margins of the intrusive and its dike-like apophyses.
Molybdenum grades generally drop off sharply in the later, inter-mineral quartz diorite dykes which often cut off mineralized veins; there is a suggestion that grades are better around these dykes due to their having superimposed another episode of mineralization on the earlier veins caused by granodiorite. In the centre of the large granodiorite mass, grades drop off to very low (0.00x per cent) MoS2 values.
Veins in the Trout Lake stockwork comprise several sets. The older veins trend southeast parallel to the major fold axes and most of the faults (135 degrees, subvertical). Secondary vein sets occur on cross-joints striking 045 degrees and dipping subvertical; and there are late subhorizontal veins. In addition, conjugate subvertical, shear-related veins, striking 005 degrees and 095 degrees, are prominent. The close spatial and temporal relationship between these veins and the Trout Lake stock suggests that hydraulic fracturing followed emplacement of magma. Furthermore, this suggests that the fracturing was caused either by the release of orthomagmatic fluids, or by hot over-pressured metamorphic or meteoric fluids.
Post-mineral faults have been observed in drill core to cut off good grade molybdenite, but in underground exposure the displacements are seen to be only minor readjustments between blocks. Only the "Z" fault which bounds the deposit on the east appears to have significant dip-slip movement. The interrelationships of crosscutting diking, veining and faulting show a suitably complex style of repeated opening of fractures and regeneration of mineralizing fluids as an intrusive differentiated at depth (Canadian Institute of Mining and Metallurgy January 1983).
Tungsten mineralization (with minor molybdenum and copper) is virtually restricted to lenses of skarn occurring as replacements of limestone bands peripheral to the main molybdenum zone. The tungsten occurs as scheelite, with pyrrhotite and minor chalcopyrite as at the nearby Copper Chief occurrence (082KNW004), or as scheelite in quartz veins with galena, sphalerite and tetrahedrite as at the Lucky Boy (082KNW003).
Skarns, manifested mainly by clinopyroxene and garnet, and hosting minor scheelite, occur as replacements of marble along faults adjacent to the Trout Lake stock. Tremolite +/- clinozoisite (calc-silicate alteration) locally replaces clinopyroxene and in turn is replaced by biotite and/or calcite, indicating that skarn predated potassic (biotite) alteration.
Traces of chalcopyrite occur throughout the system. Galena and sphalerite occur rarely in late quartz-carbonate veins cutting the molybdenite stockworks.
The property is located at 1524 metres elevation on the ridge between Wilkie (Trout) Creek and Trout Lake, 5 kilometres west-southwest of Trout Lake village and some 50 kilometres southeast of Revelstoke. Molybdenum in quartz veins was first reported in 1898 when the Molybdenum claim was staked to the south of the Lucky Boy by T.R. Davie. The Prodigal claim was staked in the same vicinity. Opencutting was reported. The claims were subsequently abandoned. Although molybdenum mineralization was among the earliest discoveries, much of the historical exploration of this area was related to a search for silver, lead, zinc and tungsten (see Copper Chief, 082KNW004 and Lucky Boy, 082KNW003). Past work on the adjacent Lucky Boy and Copper Chief comprised underground development which resulted in some ore shipments being made.
Molybdenite showings were reported in 1902 on a group comprising the Copper Chief, Ruffled Grouse, and Willow Grouse claims. These showings were explored by opencutting in 1917 by the Copper Chief Mining Syndicate. The 4 claims and a fraction were owned at that time by J.W. Livingston.
No further activity with regard to the molybdenite showings was reported until 1969 when Cascade Molybdenum Mines Ltd. optioned the Lucky Boy and Copper Chief Crown grants and about 30 surrounding located claims from Alan Marlow and Beulah Oakey. Work during 1969-70 included geological mapping, bulldozer trenching, and 992 metres of diamond drilling in 7 holes on C.H., Annex, Lucky Jay, and Copper Chief Moly claims. The option was subsequently given up.
Newmont Mining Corporation of Canada Limited in 1975 optioned from Alan Marlow and Beulah Oakey the Lucky Boy and Copper Chief groups and the Annex, LB Fr., Lucky Jay 1-3, 6, 7, 9-11, Rover 2-7, Copper Chief Moly, Copper Chief Moly 1 and 2, and TL 1-3 located claims. Work during 1975 included geological mapping, a magnetometer survey over 2 line-kilometres, and a geochemical soil survey (874 samples) over 26 line-kilometres. Work during 1976 included a geochemical. soil survey (97) samples, and 3102 metres of diamond drilling in 9 holes on C.H. (Lot 4741), Lucky Jay 1, Copper Chief Moly and Annex claims.
Newmont changed its name in February 1977 to Newmont Exploration of Canada Limited. A joint venture agreement for further exploration was signed in 1977 between Newmont (55%) as operator and Esso Minerals Canada (45%), a subsidiary of Imperial Oil Limited. A discovery hole drilled in 1977 indicated a sizable deposit of molybdenum. Deep diamond drilling in 1977-78 totalled 5873 metres in 7 holes. A program of underground exploration begun in September 1979 included 2 kilometres of adit and drifts at the 1006 metre elevation, 22,000 metres of drilling in 87 holes, and bulk sampling; this work was completed in 1981. The pipe-like stockwork deposit extends from the surface to a depth greater than 1000 metres. The property was inactive from 1982 until 2003 when a reclamation program was carried out by Newmont.
In 2004 Roca Mines Inc. acquired the property and conducted a surface drilling program. Grades and resources identified combined with strong molybdenum commodity prices and outlook indicated that the property had the potential to become a mine. The company then moved to mine development and permitting under the small mines permit. Commercial production began in October of 2007. The combined Measured and Indicated resource estimate calculated in a 2004 technical report was 42.94 million tonnes grading 0.12 per cent Mo; converted to Mo from MoS2 using a 1.6681 conversion factor (Technical Report on the Max Molybdenum Property, September 20, 2004; www.rocamines.com).
First molybdenum contained in concentrate was shipped December 11, 2007. Production was suspended between September 21, 2010 and July 27, 2011. Operations were suspended October 3, 2011.