Banded massive sulphide with galena and sphalerite layers
Virtual Museum ID: 19-DP04
Banded massive sulphide with galena and sphalerite layers.
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:Dave Pighin (DP)
Virtual Museum ID:19-DP04
Date Added to VM:2019-06-16
Sample Origin:Kitimat-Stikine A, BC
Specific Site:North Star Mine
Datum:09 (NAD 83)
Primary Features:Banded massive sulphide with galena and sphalerite layers
Primary Mineral Formula:(Zn,Fe)S, PbS
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:Stuhini Group/Hazelton Group
Geological Period:Upper Triassic/Lower-Upper Jurassic
Stratigraphic Age:237- 152.1 Million Years ago
Minfile ID:103P 189
The North Star mine is situated on the west bank of the Kitsault River, 23 kilometres north of the town of Alice Arm. Between 1919 and 1921, a small tonnage of silver ore was mined from this deposit.
The area is underlain by a sequence of volcanics and sediments of the Upper Triassic Stuhini Group and the Lower-Upper Jurassic Hazelton Group. The sequence is folded into the doubly plunging, north-northwest trending Kitsault River syncline. This sequence has been regionally metamorphosed to greenschist facies.
The North Star occurrence comprises a stratiform, volcanogenic silver-zinc-lead barite exhalative deposit that is likely the same ore horizon as the Dolly Varden deposit (103P 188) to the south. As with the Dolly Varden, this deposit is underlain by Hazelton Group andesitic crystal vitric (shard) tuff and overlain by andesitic ash tuff that have undergone sericitization, silicification and propylitization due to regional metamorphism and hydrothermal alteration.
The North Star deposit occurs on the steeply dipping west limb of the Kitsault River syncline. It is cut by a number of steeply dipping, northwest striking faults and numerous northeast striking, near vertical mafic dikes. The deposit strikes northeast, dips 45 degrees northwest and varies from 1 to 24 metres in width. The deposit contains a lens-shaped zone of higher silver grades that extends 107 metres along strike, 107 metres downdip and varies from 1.5 to 9.8 metres in width.
The mineralogy of the North Star deposit is similar to that of the Dolly Varden West orebody (103P 188), consisting of layers, disseminations and stringers of sphalerite and galena with minor pyrite, chalcopyrite and tetrahedrite and a trace of native silver and pyrargyrite in a gangue of calcite, quartz, siderite and barite. This carbonate-sulphate-sulphide exhalite exhibits pronounced layering and vertical mineral zonation, with a pyrite-rich base and a sphalerite-galena-rich top.
The North Star deposit has seen very limited production from underground workings. In 1919, Alice Arm Silver Mines Co. sent a trial shipment of 24.5 tonnes of unsorted ore grading 1229 grams per tonne silver to the copper smelter at Anyox. In 1921, 77 tonnes of hand-sorted ore grading 754 grams per tonne silver were shipped to the Anyox Smelter.
Combined (proven, probable) reserves at North Star are 127,901 tonnes grading 401.4 grams per tonne silver (George Cross News Letter May 25, 1987). See Torbrit (103P 191) for more details.
In 1990, Dolly Varden Minerals Inc. conducted geological mapping, and diamond drilling on portions of the North Star, Dolly Varden (103P 188) and Torbrit (103P 191) deposits and the V zone (103P 010, 18, 196). The Northstar mine area was tested by eight NQ drillholes totalling 4119 metres. Refer to Dolly Varden for a comprehensive work history of the area and 2015 resource estimates.
In 2010, Dolly Silver Corporation conducted an exploration program on the Dolly Silver property which consisted predominantly of a detailed stream sediment sampling survey with associated geological mapping, prospecting, rock and soil sampling. A total of 81 rock samples, 19 soil samples and 150 stream sediment samples were collected. A concurrent helicopter-borne time domain electromagnetic (VTEM), magnetic and radiometric survey over both the Dolly Silver and Dolly Varden properties was also completed. Flight line spacing was 200 metres over the Dolly Silver property and 100 metres over the Dolly Varden property with a total of 941.7 line kilometres of data collected.
In 2017, Dolly Varden Silver Corporation announced plans for 12,000 metres of diamond drilling at the Dolly Varden silver project. The project consists of the Torbrit (103P 191), Dolly Varden (103P 188), Wolf (103P 198), and North Star deposits. Drilling between the Torbrit and Wolf deposits resulted in a new discovery (Central zone), with results that included 16.10 metres (13.19 metres true thickness) grading 269.0 grams per tonne silver, 0.30 per cent lead and 0.21 per cent zinc. Follow-up drilling confirmed this discovery, returning results of 7.15 metres (6.72 metres true thickness) grading 1180.7 grams per tonne silver, 1.83 per cent lead and 0.26 per cent zinc. Drilling also discovered an eastern fault offset of the Torbrit deposit (Torbrit East, 103P 190), with assays including 13.00 metres (9.96 metres true thickness) grading 244.8 grams per tonne silver, 0.14 per cent lead and 0.09 per cent zinc. Within this interval was 5.00 metres (3.83 metres true thickness) grading 481.9 grams per tonne silver, 0.21 per cent lead and 0.12 per cent zinc (Information Circular 2018-1, page 137).