Rhyolite tuff

Virtual Museum ID: 19-T1-01

Specimen Summary

ivory to pale green with streaky brown wisps; brown wisps probably arise from disseminated, foliation-parallel pyrite that is oxidized, enhanced by surface weathering; 2% quartz eyes; 5% feldspar phenocrysts; tuff banding flows around phenocrysts

Specimen Data


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Collection Details

Original Collection:

Smithers Exploration Group (SEG)

Sub Collection:


Collection ID:


Virtual Museum ID:



Date Added to VM:


Location Information

Sample Origin:

Vancouver Island, B.C.

Specific Site:

Mt Sicker

UTM Easting:


UTM Northing:



10 (NAD 83)

Coordinate Accuracy:

Specimen Details

VM Category:


Primary Features:

Rhyolite tuff

Primary Mineral Formula:

Primary Category:

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:

Sicker and Buttle Lake groups

Geological Period:


Stratigraphic Age:


Geological Belt:


Geological Terrane:


Minfile ID:

092B 001

Site Details:

The Lenora past-producer is located on the western slopes of Mount Sicker, approximately 1.5 kilometres east of the Chemainus River.

Several past-producers are located on Mount Sicker in the Cowichan uplift, one of three geanticlinal uplifts that expose rocks of the Paleozoic Sicker and Buttle Lake groups on Vancouver Island. Cretaceous sediments of the Nanaimo Group unconformably overlie the Paleozoic rocks; the contact is marked by a basal conglomerate containing volcanic fragments derived from the Sicker Group. The local stratigraphy is disrupted by folding, faulting (pre-Triassic as well as Tertiary) and the intrusions of two gabbro sills (informally known as the Mount Hall Gabbro) that are coeval with the Upper Triassic Karmutsen Formation. The target of exploration activity has been the volcanogenic, polymetallic massive sulphides that are hosted within felsic volcanic tuffs of the McLaughlin Ridge Formation (Sicker Group) and restricted to a belt running from Chipman Creek to Mount Richards, in the hangingwall of the Fulford fault.

Massive sulphides were discovered on Mount Sicker in the late 1800's and production issued from three separate underground mines (Lenora - 092B 001, Tyee - 092B 002 and Richard III - 092B 003) for several years. These mines were later held as one operating mine, the Twin J mine (1942-1952). The Twin J mine was examined by J.S. Stevenson in the 1940's and the following description is derived from his paper (Geology of the Twin J Mine; Structural Geology of Canadian Ore Deposits, Volume 1, The Canadian Institute of Mining and Metallurgy, 1948). The rocks in the mine, and nearby, include cherty tuffs, graphitic schists, rhyolite porphyry and diorite. The chert and graphitic schists together form a band of sediments 30 to 45 metres wide that near the workings are at least 640 metres long. The trend of the band and the strike of the sediments are 110 degrees. The dip of the sediments is 50 degrees southwest. Where relatively undeformed, the rocks are slaty, where moderately deformed their laminae are bent into small canoe-shaped folds, and where intensely deformed, either by close folding or shearing, they are highly schistose.

Rhyolite porphyry and diorite are the two most widespread rocks in the area. Rhyolite porphyry sills follow the folding of the sediments and dykes cut early phases of the diorite. Two phases of the diorite, fine grained and coarse grained, are present. Fine-grained diorite occurs as sills in the sediments; coarse-grained diorite is found as irregular intrusive bodies, and as well-defined dykes. Although all phases of the diorite are younger than the sediments, some phases are older and others younger than the rhyolite porphyry.

Two types of ore are found in association with cherty tuffs and graphitic schists: a barite ore consisting of a fine grained mixture of pyrite, chalcopyrite, sphalerite and a little galena in a gangue of barite, quartz and calcite; and a quartz ore consisting of mainly quartz and chalcopyrite.

The two main orebodies, known as the North orebody and the South orebody, are long, lenticular bodies lying along two main dragfolds in the band of sediments. The North orebody measures about 500 metres along strike, 37 metres downdip and from 0.3 to 3 metres in thickness. The South orebody, which is 46 metres from the North, and has its upper limit 45 metres higher, measures 640 metres along the strike, 45 metres downdip and is about 6 metres in thickness. Most of the ore mined in the early period came from the South orebody, but most of that mined by Twin J came from the North orebody.

Two main faults, striking east and nearly vertical, displace the orebodies. The north fault is between the two orebodies, and in going westward strikes into the South orebody at a small angle. This fault displaces the south orebody about 60 metres upward and an unknown distance eastward with respect to the North orebody. Long sections of barite drag-ore may be seen in the north fault below the South orebody. The south fault is south of the South orebody. Several diagonal faults cut the orebodies, but displace them only slightly horizontally and vertically. A few flat, or very gently dipping faults also cut the orebodies; but these displace the ore even less than most of the diagonal faults. In addition to movement along well-defined faults, considerable slippage has occurred between sharply folded beds in the graphitic schists.

A regional silicified and pyritized fracture zone can be traced by widely separated, mineralized outcrops, from Mount Richards on the east through the Twin J on Mount Sicker To Mount Brenton on the west, a total of 13 kilometres. The displacement along this break is unknown. At the Twin J, the fracture zones are manifested by vertical silicified zones on the south sides of both the North and South orebodies and by post-mineral breaks such as the north and south faults.

The first claim in the area was staked in 1895 by F.L. Sullivan, T. McKay and Henry Buzzard. The partners were later joined by Harry Smith.

The Lenora mine, worked between 1898 and 1903 (inclusive) and in 1907, produced 321,886 grams of gold, 8,706,817 grams of silver and 3,226,034 kilograms of copper from a total of 71,650 tonnes mined. The Tyee mine was worked intermittently from 1901 to 1909 producing 762,553 grams of gold, 13,725,069 grams of silver and 5,840,593 kilograms of copper from a total of 152,668 tonnes mined. The Richard III mine produced, in three years between 1903 and 1907, 22,830 grams of gold, 522,714 grams of silver and 113,604 kilograms of copper from a total of 4,903 tonnes of ore mined (Mineral Policy data).

The three mines were amalgamated and operated intermittently between 1942 and 1952 as the Twin J mine. From a total of 48,082 tonnes mined, the operation produced 63,730 grams of gold, 2,002,971 grams of silver, 364,755 kilograms of copper, 164,587 kilograms of lead, 1,926,111 kilograms of zinc and 4,546 kilograms of cadmium (Mineral Policy data). The property has undergone steady exploration by various companies from 1964 to present. Based on mapping, geochemical and geophysical surveys, trenching and diamond drilling from 1967 to 1970, ore reserves were estimated at 317,485 tonnes grading 1.6 per cent copper, 4.11 grams per tonne gold, 140.54 grams per tonne silver, 0.65 per cent lead and 6.6 per cent zinc (Northern Miner - September 25, 1969).

In 2010 and 2011, Rock-Con Resources completed a program of prospecting and rock sampling on the Mount Sicker property. A 6.0 metre chip sample (7D) from the Lenora pit, near the adit, assayed 4.8 grams per tonne gold, 176 grams per tonne silver, 2.78 per cent lead, 1.19 per cent copper and 13.85 per cent zinc. Other chip samples assayed up to 16.9 grams per tonne gold, 155 grams per tonne silver, 10.9 per cent copper, 2.78 per cent lead and greater than 30.0 per cent zinc over 6.0 metres (Assessment Report 32278).

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