Vault gold-silver veins, Okanagan Falls, Osoyoos Mining Division, British Columbia, Canadai

Regional Level Types
Vault gold-silver veins	Prospect
Okanagan Falls	- not defined -
Osoyoos Mining Division	Division
British Columbia	Province
Canada	Country

The Vault gold-silver vein prospect is located about 4 kilometres north-west of the small community of Okanagan Falls, about 15 kilometres south of Penticton, British Columbia, in the Osoyoos Mining Division.
There is a detailed description of the property, including regional geology, on the British Columbia “Minfile” site, current to 2008. Interested readers are encouraged to access this source, and also to refer to Church (1967, 1973) for details of the geological setting. Selected portions of the Minfile account are quoted below:
“The Vault occurrence lies within the eastern part of the White Lake basin, a thick accumulation of Eocene Penticton Group volcanic rocks, interlayered with clastic sedimentary rocks which are largely of volcanic derivation. The Eocene rocks rest unconformably on Triassic metavolcanic and metasedimentary rocks of the Independence, Old Tom and Shoemaker formations, and Jurassic granitic intrusions. The White Lake basin forms a topographic low and is truncated by early gravity faults. The units generally dip to the east and are folded and faulted.”
“Drill information indicates that alteration is dominated by an elongate zone of intense silicification and stockwork veining occurring above the Kitley Lake Member/lower Marama Formation contact. In drill core, the intensity of silicification appears to increase with the frequency of quartz veining. Within the area of mineralization, silicification is pervasive and the replacement of wallrock by chalcedonic quartz is locally evident. Clay alteration is common adjacent to fault zones and is particularly notable as feldspar alteration in trachytic flows and breccias. Minor muscovite and green micaceous minerals are also present in altered sections. Hematite, calcite and chlorite alteration are poorly developed in all units and are usually confined to fractures, vein margins and breccia matrix or fragments. Calcite veinlets usually crosscut silicic alteration and veining.
Gold-silver mineralization is associated with a discontinuous, east trending, steeply dipping quartz vein system on the north limb of a northeast-trending syncline. Veining is concentrated primarily in lower Marama rocks, where the porosity and permeability of the volcanic breccias and tuffs are highest, although a few minor gold-bearing veins have been encountered in the Kitley Lake and upper Marama formations. Intense silicification and weak, very fine grained pyritization accompanies much of the mineralization.
Near-surface mineralization, where silicification is less intense, is generally anomalous in precious metals, but below an estimated economic grade of less than 3 grams per tonne gold. With increased depth, silicification becomes more intense and the average grade increases to the 5-10 grams per tonne range, in places over substantial widths. Gold and silver are typically not visible to the naked eye, but are considered likely to occur as native elements, or possibly as electrum. Silver-gold ratios in the mineralized zones are highly variable, averaging 9.8:1. The ratios tend to be lowest with higher gold values.
Veins in the main mineralized zone have typical adularia- sericite-type epithermal textures and mineral assemblages. Finely banded and bladed chalcedonic quartz, ankeritic carbonate and minor alkali feldspar (adularia) are the main vein components. Veins range in size from fine irregular anastomosing veinlets a few millimetres thick, to larger veins about 10 centimetres wide. Some exceptionally large veins are up to about 30 centimetres in width. They commonly display multistage growth textures, such as scalloped colloform banding, bladed cockscomb intergrowths and drusy cavities. Where the vein minerals occur as breccia matrix, some breccia fragments are rimmed with finely banded quartz and occur in a matrix of black, grey and white silica. Some of the most significant gold values are associated with complex multistage veining. In a number of intersections the veins have been brecciated and subsequently rehealed by the addition of banded silica. In other areas, banded quartz clasts are a significant component of the breccia.
The sulphide content associated with mineralization is typically low, although some sections are highly oxidized, with 5 to 10 per cent pyrite which is very fine grained and may occur as disseminations, fracture or vein-breccia fillings and thin veinlets. Minor pyrrhotite with sphalerite intergrowths is also associated with pyrite. Native gold is observed associated with pyrrhotite.”

Giles Peatfield comments:
The discovery history of the Vault veins is interesting. There are several old mines and occurrences, generally veins, in older rocks in the general region; in some cases, work on these dates back as far as the late 1800’s. Just to the east of Okanagan Falls, the Dusty Mac gold-silver vein property has several old adits on vein occurrences in younger (Eocene) rocks, similar to those on the Vault property. The Vault veins were not targeted until much later. Church (1970), describing the Dusty Mac deposit, where serious work began in 1968, published a map of the general region on which an occurrence of “Gossan” is noted in the area that became the Vault property. This was examined and staked in 1982 by local geologist M. Morrison; exploration began on the claims in 1983. Refer to the Minfile article for a description of the various work programs.
There has been no production from the veins. Morrison (2001) offered the following information: “The first discovery was the Central Zone on the Vault 1 mineral claim which contains an estimated geological reserve of approximately 1.3 million tonnes of 2 grams per tonne (gpt) gold. The second discovery was the North Vein on the Vault 2 mineral claim which has a drill indicated reserve of 152,000 tonnes of 14 gpt gold plus minor silver values) to a depth of 200 metres.” I can find no further information regarding these “reserve” figures, and believe it is extremely unlikely that they would stand up to serious scrutiny – in any event they should not be used, and are quoted only as a caution.
Comments on the Minerals Reported:
Many of the mineral identifications are by field observation, some are by microscopy, and a few are confirmed by X-ray analysis; comments regarding methods of identification are included in the notes below.
Amphibole group: Littlejohn (1986) reported both tremolite and hornblende in thin sections of altered andesitic and basaltic rocks.
Apatite group: Littlejohn (1986) and Xiong (1993) reported ‘apatite’ but neither gave more specific data. Given the presence of fluorite (q.v.) it is possible that it is fluorapatite, but this is not confirmed.
Ankerite?: Meyers (1989) mentioned ‘ankeritic carbonate’ in the Vault veins, but gave no analytical data. No other referenced worker mentioned ankerite, and I would regard it as tentative.
Calcite: Calcite is common and reported by all referenced workers.
Chalcopyrite: Meyers (1989) wrote that “Elevated pyrite content does not generally correlate with significant gold values. Base metal sulphides such as chalcopyrite, galena and sphalerite, do not appear to be related to precious metal distribution on the Vault property.” This is a rather ambiguous statement, and in any event, it is the only (unconfirmed) reference to galena, which I have not included in the mineral list. Xiong (1993) provided more detail, based on examination of polished sections, describing stockwork ‘ore’ with disseminated sulfides. “Sometimes sulfides congregate as massive sulfides. This type of mineralization is earlier than quartz-vein mineralization as indicated by cross cutting relations. The stockwork mineralization is mainly composed of sulfides, which have botryoidal textures . . . , and a small amount of quartz and calcite. Sphalerite and pyrrhotite are earlier than pyrite, whereas chalcopyrite is later than pyrite.”
Chlorite group: Most workers have reported ‘chlorite’ as an alteration mineral, but have provided no more specific identification.
Dolomite: Littlejohn (1986) and Xiong (1993) both reported dolomite in thin sections.
Epidote: Xiong (1993) reported ‘epidote’ in propylitic alteration at considerable depth in drill holes.
Feldspar group: There are many references to various feldspars – the following species have been reported: ‘plagioclase’, ‘K-spar’, sanidine, adularia (X-ray confirmed by Xiong, 1993), and albite (X-ray confirmed by Xiong, 1993).
Fluorite: Xiong (1993) reported fluorite in Stage III veins, and used it in fluid inclusion studies.
Goethite: Xiong (1993) reported goethite (X-ray confirmed), as a minor supergene mineral.
Gold: Xiong (1993) noted that “Native gold is observed in association with pyrrhotite . . . .”
Hematite: Littlejohn (1986) identified hematite in thin sections. Xiong (1993) reported that “Some of the pyrrhotite is altered by late hematite.”
Jarosite: McClintock (1982) made numerous references to jarosite mixed with limonite in the near-surface environment; Xiong (1993) confirmed jarosite by X-ray analysis.
Kaolinite: McClintock (1982) described this as an alteration of feldspar; Xiong (1993) confirmed kaolinite by X-ray analysis.
Limonite: This is a near-surface alteration product of weathering of pyrite, reported by several workers. Littlejohn (1986) identified it in thin section.
Marcasite: There are numerous references to marcasite, by A. B. Mawer in core logging (Read 2005). This is the only worker to report the mineral, but I think it likely that he was correct.
Mica group: Various workers have identified biotite, sericite and muscovite. Xiong (1993) confirmed muscovite by X-ray analysis.
Montmorillonite: This was identified in thin section by Littlejohn (1986).
Pyrite: This is ubiquitous, reported by all workers. It is generally fine-grained and in most cases disseminated, although it is locally semi-massive.
Pyroxene group: Littlejohn (1986) identified augite in thin sections of basalt and trachyandesite.
Pyrrhotite: Reported by Xiong (1993), who noted it in both stockwork and vein mineralization. See note above for gold.
Quartz: This is ubiquitous, as generally chalcedonic vein material and silica flooding.
Sphalerite: See note above for chalcopyrite. Also, Xiong (1993), describing the vein mineralization, wrote that “Pyrrhotite is minor; it intergrows with sphalerite. Sphalerite is anhedral, and is minor in abundance. Both pyrrhotite and sphalerite are later than pyrite.”
Talc: A. B. Mawer (Read 2005) identified talc in core logging.
Zeolite? Oddy (1984) logged a trachyandesite porphyry with “. . . clay or zeolite filled rounded vesicles.” Zeolites are to be expected in these rocks, but there is no way to tell from the description which species is (or are) present.
NOTE: most of the rock types are field designations from reports by various workers.

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.
Consultant 1985 to 2016

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Link to British Columbia Minfile:	082ESW173

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