Primer porphyry copper prospect, Missezula Lake, Similkameen Mining Division, British Columbia, Canadai

Regional Level Types
Primer porphyry copper prospect	Prospect
Missezula Lake	- not defined -
Similkameen Mining Division	Division
British Columbia	Province
Canada	Country

The Primer porphyry copper prospect is located immediately east of the south end of Missezula Lake, near the head of Summers Creek, about 34.5 kilometres north of Princeton and 100 kilometres south of Kamloops, British Columbia. Refer also to Minfile Number 092HNE 055 (PRIMER (SOUTH ZONE), etc.) and (092HNE 110 (NELLIE 28)).
There is an extended description of the property on the British Columbia “Minfile” site, current to 2021, to which interested readers are referred. Relevant portions pertaining to geology are quoted below:
“This region in the vicinity of Missezula Lake is underlain by the Eastern volcanic facies of the Upper Triassic Nicola Group, comprising mafic to intermediate, augite and hornblende porphyritic pyroclastics and flows, and associated alkaline intrusions. The intrusions vary in composition from diorite to monzonite and are thought to be comagmatic with the Nicola Group, ranging in age from Upper Triassic to Lower Jurassic. Much of the copper mineralization and associated alteration frequenting this portion of the Nicola Belt can be attributed to the emplacement of such intrusions.
The deposit is largely hosted in variably plagioclase and hornblende porphyritic andesite of the Nicola Group (Eastern Belt, Bulletin 69) [Preto, 1979]. A body of diorite and microdiorite, possibly related to the andesite, lies immediately northwest of the deposit. Short sections of schist and occasional hornblende porphyritic diorite dikes occur at depth in the andesite.
The hostrocks are hydrothermally altered in areas of stronger shearing and fracturing. Secondary minerals include chlorite, epidote, albite, carbonate, sericite and kaolinite. The andesite is cut by a prominent set of steeply dipping, north-northwest–striking shears and fractures. Numerous northwest- and northeast-striking shear zones are also evident. Gypsum (selenite) veins are frequent, while quartz and calcite veins are less common.
Mineralization consists of pyrite and chalcopyrite, generally as veins and fracture fillings, but also as disseminations and blebs. Gossanous zones of stronger shearing, fracturing and alteration contain 3 to 20 per cent pyrite, 1 to 3 per cent magnetite and trace to 1 per cent chalcopyrite. Chalcopyrite to pyrite ratios are approximately 1 to 3. Malachite and azurite accompany chalcopyrite and pyrite in trenches with intensely fractured and sheared andesite. These surface exposures suggest stronger mineralization is controlled by shearing. Disseminated chalcopyrite and pyrite are also found in chloritized andesite. Magnetite occurs as veinlets and is present in chalcopyrite seams in minor amounts. Chalcopyrite is also associated with epidote alteration and to a minor extent, carbonate-quartz veining.”
Giles Peatfield comments:
As far as can be ascertained, there are no radiometric dates available for the intrusive rocks in the Primer prospect area. Preto (1979) provided fossil evidence that the Nicola volcanic rocks are of Late Triassic age, and in describing intrusive bodies in the area wrote that “Wherever these stocks are surrounded by Nicola fragmental volcanic rocks, a remarkable number of clasts of the intrusive are found in the nearby volcanic rocks thus indicating a close overlap of ages between intrusive and extrusive or volcaniclastic rocks. The intrusive is younger than part of the volcanic succession, which it cuts, and older than part of it, to which it supplied clasts. These relationships suggest that most of these small stocks are the high level, intrusive part of volcanic centres which periodically extruded the surrounding volcanic rocks but which were soon after denuded and eroded to supply debris for slightly younger parts of the succession.”
Regarding mineral resources, the only information available for the Primer prospect is contained in Pilcher and McDougall (1976) who reported a “Grade and Tonnage” of 0.20% Cu, 23Mt [presumably short tons], quoting their source as “Rio Tinto staff”. Schroeter (1995) simply repeated this information with no additional data. This resource estimate, quoted by Minfile, would not be compliant with National Instrument (NI) 43-101 standards; there do not appear to be any more recent estimates. The deposit as presently known is small and of low grade.
The Primer porphyry copper prospect is included in the USGS compilation by Singer et al. (2008). The references quoted in this report for the deposit are Pilcher and McDougall (1976) and Schroeter (1995). The information given by Singer et al. (2008) is incomplete.

Giles Peatfield comments on the minerals reported:
The following comments, derived from several reports, give some details of the various minerals reported from the Primer porphyry copper prospect and immediately surrounding area. A word of caution here is that the work of McMillan (1964) and Le Couteur (2008) was based on a limited number of specimens, and therefore the results may not be wholly representative. Le Couteur’s work involved microscopy and electron microprobe analyses.
Amphibole group: McMillan (1964) reported hornblende or amphibole, but gave few details. Le Couteur (2008) provided more details, writing that “In sample 241.0 m the amphibole is fresh and glassy, shows only minor ?chloritic streaking, and occurs as olive-green subhedra and euhedral . . . elongate columnar crystals to 2 mm long, that in cross section have the characteristic shape and cleavage of amphiboles. Analyses . . . show the amphibole has a magnesio-hornblende composition. In most other samples amphibole shows moderate to severe alteration to chlorite . . ., and to a brown biotite-like mineral . . . .”
Ankerite?: Gilmour and Koffyberg (2010) noted numerous instances of ankerite in drill core logging, although in some cases they were not sure if the mineral was ankerite or dolomite. Le Couteur (2008) noted that in the sections he examined “Calcite varies in appearance even in the same vein or aggregate, from transparent and uncoloured to dense, pale brown and only slightly translucent, and it was suspected that perhaps some was dolomite, ankerite or siderite. However, in examples that were analysed only ordinary calcite with minor Fe was found.” There may be iron-rich carbonate here, but the species are not precisely known.
Apatite: McMillan (1964) noted apatite in thin sections of altered porphyry. Le Couteur (2008), describing primary igneous minerals in his polished thin sections, noted that “Minor apatite forms scattered clear stubby rods with hexagonal cross-sections to about 0.2 mm across. Analysis . . . indicates these are chlorapatites.” Further, describing alteration minerals, he noted that “In [sample] 47.1 m a thin veinlet of apatite was noted. Analysis indicates this lacks the chlorine found in the primary igneous apatite.”
Azurite: Reported by McKechnie (1964) in trenches where fracturing is prominent. Nebocat (1980) wrote that “Azurite is concentrated within narrow fault bounded zones (1 meter to 3 meters) in trenches 2 and 3.”
Baryte: Le Couteur (2008) wrote that “A few grains of barite [sic] were noted in [sample] 241 m [in] a veinlet about 0.1 mm wide, along with calcite and albite . . ., and some curious lath-like barite [sic] was noted in [sample] 223.0 . . . associated with bornite.”
Bornite: Nebocat (1980) noted that “Disseminated bornite was seen in one location only, approximately 8 meters south of station E in trench 2.” Gilmour and Koffyberg noted numerous occurrences of bornite in their core logging. Le Couteur (2008) provided much more detailed information based on examination of polished sections, noting that “Small amounts of bornite are present in [samples] 223m and 241 m as scattered anhedra to about 0.4 mm across. Some bornite in [sample] 223.0 m has some inclusions and alterated [sic - altered?] areas . . . of a grey mineral (?chalcocite). Analyses . . . do show an increase in Cu and decrease in S, but the compositions are not typical of chalcocite. Analyses of several bornites also do not give typical proportions for Cu and Fe . . . . Bornite is associated with calcite, epidote, hematite and albite in [sample] 223 m and with prehnite, epidote and chalcopyrite in [sample] 241m.”
Calcite: For Le Couteur’s (2008) description of calcite, refer to the comment above for ankerite.
Chalcocite?: See comment above for bornite.
Chalcopyrite: This is common here, on fractures or in veins. Le Couteur (2008) wrote that “Chalcopyrite occurs in [sample] 241m as irregular, angular anhedra up to 0.1 mm, with bornite associated with a 2 mm wide envelope of calcite-epidote-prehnite alteration bordering a narrow calcite vein. Only a few tiny grains of chalcopyrite were noted in [sample] 223m. In [sample] 16.7 m trace disseminated chalcopyrite occurs as anhedra and clusters to 0.2 mm across of anhedral as small as 0.05 mm across . . . .”
Chlorite group: Nebocat (1980) and Gilmour and Koffyberg (2010) reported “chlorite” as an alteration mineral but gave no specific data. Le Couteur (2008) provided more information, writing that “Chlorite is present in all samples, and in various forms. It particularly replaces amphibole . . . , also forms ragged patches . . . , also occurs in veins with calcite, and may replace plagioclase . . . .”
Clausthalite: This is the mineral of most interest at the locality. Le Couteur (2008) wrote that “About 35 tiny grains of clausthalite are present in [sample] 223m, mostly as inclusions within bornite . . . . Some grains are rounded, others elongate rods, up to 30 microns across but mostly smaller than 10 microns across.” Le Couteur’s analysis of a grain of this mineral yielded 74% Pb and 26% Se, which when converted to molar values gives a nearly 1:1 ratio, thus confirming the composition as PbSe. This appears to be the first Mindat occurrence of the mineral for British Columbia.
Copper: Le Couteur (2008) reported that “Traces of native Cu are present in [core sample] 241 in the core . . . , but were not present in the part of this sample that was sectioned.”
Epidote: McMillan (1964) noted epidote in thin sections of altered monzonite and monzonite porphyry. Le Couteur wrote that “Epidote is a minor constituent in several samples, and occurs as small, irregular-shaped clumps of granular aggregates.”
Feldspar group: Both plagioclase and K-feldspar have been identified in rocks from this locality. Le Couteur (2008) provided details regarding plagioclase, noting that most of the primary plagioclase was almost completely altered to sericite. He also saw a small amount of secondary albite, noting that “Minor new albite forms fine-grained mosaics with quartz in some samples, and also occurs in veins with calcite, chlorite and barite (Figure 36 to 40). As noted above, much phenocrystic plagioclase is also converted to albite.” As regards K-spar, Le Couteur (2008) noted that sample off-cuts were stained for K-spar and in two cases a small amount of yellow stain was evident; he did not see a large amount of K2O in his analysis of the matrix material, but concluded that a small amount of K-spar might be present. McMillan (1964) noted several examples in thin sections where orthoclase appeared to be an alteration of plagioclase.
Gypsum: Nebocat (1980) reported that “A late stage alteration seen in every hole is widespread gypsum veining. It starts at considerable depth, the nearest it comes to surface is 65 meters in hole 80-2.”
Hematite: Le Couteur (2008), describing polished thin sections, wrote that “Hematite occurs in 2 forms, principally as a replacement of primary magnetite . . . , but also as bundles of columnar or lamellar crystals (specularite?) associated with bornite . . . .”
Ilmenite?: Le Couteur (2008) wrote that “A near-opaque, yellowish mineral [which he called leuxocene] replaces magnetite, particularly in [sample] 16.7 m and appears to be ill-defined mixtures of Ti and Fe oxides. In some cases it appears these were formerly Ti-bearing magnetite and some retain a meshwork of lamellae that probably are ilmenite . . . .”
Kaolinite? Nebocat (1980) described some intrusive rocks as “kaolinized”, but gave no details. Other workers did not mention the mineral. I would regard this as a tentative identification.
Limonite: Nebocat (1980), describing a highly altered intrusive rock, wrote that “Disseminated pyrite and limonite coatings on fractures occurs [sic] throughout.” Gilmour and Koffyberg noted numerous instances of “limonite” in the course of core logging.
Magnetite: Le Couteur (2008) wrote that “As well as primary magnetite phenocrysts and smaller grains in the matrix, magnetite also occurs as an alteration mineral in [samples] 187.1m and 223m. Analysis of magnetite in a dense swarm of grains (after amphibole? . . .) in [sample] 223.0m showed 4% Cr2O3.”
Malachite: Reported by McKechnie (1964) in trenches where fracturing is prominent. Nebocat (1980) wrote that “Malachite coats fractures quite evenly throughout the altered syenite with no evidence of preference to zones or select fracture sets.”
Mica group: Most workers have reported both sericite and biotite. Le Couteur (2008) gave somewhat more detailed information – to quote his work “Sericite is present in all samples, replacing plagioclase in amounts ranging from a light flecking of tiny scales . . . to heavy replacements by fairly coarse white mica . . . .” and “Sample[s] 241 m and 223m contain a minor amount of medium to dark brown, ragged, irregular anhedra . . . to about 0.4 mm across that are interstitial, or encrust or form inclusions in amphibole. These modes of occurrence suggests[sic] this is either a late magmatic mineral or perhaps an alteration mineral, or both. However, it also occurs as veins in 241m . . . and here it is clearly secondary. The optical properties and even the composition are a little odd for biotite, and the mineral may actually be hydrobiotite.”
Molybdenite: Gilmour and Koffyberg (2010) reported, in the drill log for Hole No. 694-012, “Tr[ace] molybdenite at 33.0 m as small bebs [sic – blebs] in bornite‐calc[ite]‐c[halco]py[rite] veinlets.”
Neotocite?: Nebocat (1980), describing the surface oxidation of copper minerals, wrote that “Neotocite occurs as small pitchy black masses throughout the mineralized syenite and to a minor extent in the unmineralized rock where it has migrated across a fault interface.” This seems to be an uncertain identification, as neotocite is not a copper mineral. Was he actually seeing tenorite?
Prehnite: Le Couteur (2008), describing a polished thin section numbered 241m, wrote that “A little prehnite . . . is present in . . . a vein and its surrounding 2 mm wide envelope, and is associated with chalcopyrite and bornite.”
Pyrite: Pyrite is common, but according to most workers is sparse and generally fine grained.
Pyrolusite: Nebocat (1980), describing a hornblende diorite porphyry, wrote that “Where fractured, the diorite is extensively veined with a fleshy-pink zeolite, probably laumontite, and pyrolusite.”
Pyroxene group: Gilmour and Koffyberg, in their drill core logging, mentioned numerous occurrences of “augite” but gave no further detail. McMillan (1974) identified both orthopyroxene (hypersthene) and clinopyroxene in thin sections of monzonite and diorite. Note that hypersthene is no longer a valid mineral name.
Quartz: McMillan (1964) found quartz in a few of is thin sections, in some cases derived from alteration of feldspar. Le Couteur (2008) found, in polished thin sections, that “. . . rounded patches of mosaic quartz are present in small amounts . . . .” Gilmour and Koffyberg (2010) noted numerous “quartz-carbonate stringers” in both intrusive and extrusive rocks.
Rutile: Le Couteur (2008) wrote that “Minor amounts of very fine-grained rutile is [sic] present in many samples, typically as dispersed spots in amphibole carcasses that have been converted to chlorite . . . . The grains are often elongate and up to about 0.01 mm long.”
Titanite: McMillan (1964), reporting on a thin section of altered monzonite porphyry, reported “sphene” but gave no dehttps://mail.google.com/mail/#inboxtails.
Zeolite group: See comment above for pyrolusite.
Zoisite: McMillan (1964), reporting on a thin section of altered andesite, reported hornblende replaced by zoisite.
Giles Peatfield comments on the rock types reported:
These rock names are derived from the several reports used in this review. Some may be alternate names for the same rock type, but I have chosen to list them all. Be aware that in most cases these are field names.

Giles Peatfield
BASc. (Geological Engineering) University of British Columbia 1966.
PhD Queen's University at Kingston 1978.
Worked for Texas Gulf Sulphur / Texasgulf Inc. / Kidd Creek Mines - 1966 to 1985.
Vancouver based consultant 1985 to retirement in 2016

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Link to British Columbia Minfile:	092HNE056

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References