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File Created: 30-May-1988 by Laura L. Coughlan (LLC)
Last Edit:  04-Apr-2022 by Karl A. Flower (KAF)

Summary Help Help

NMI
Name GRIZ 3, GRIZ, A 1-8, THORN Mining Division Atlin
BCGS Map 104K068
Status Showing NTS Map 104K10E
Latitude 058º 36' 15'' UTM 08 (NAD 83)
Longitude 132º 35' 11'' Northing 6498513
Easting 640230
Commodities Silver, Lead, Zinc, Gold Deposit Types I05 : Polymetallic veins Ag-Pb-Zn+/-Au
Tectonic Belt Intermontane Terrane Cache Creek, Stikine, Plutonic Rocks
Capsule Geology

The area of the Griz 3 showing is underlain by Paleocene to Eocene Sloko-Hyder Plutonic Suite largely consisting of quartz monzonite and quartz-feldspar porphyry which have intruded Lower Jurassic sediments of the Takwahoni Formation, Laberge Group and volcanic rock of the Upper Triassic Stuhini Group.

The Griz 3 property is largely underlain by quartz-feldspar porphyry which is extremely variable in composition. It is fine-grained to aphanitic, porphyritic with mainly plagioclase phenocrysts and less commonly quartz phenocrysts. It varies from pink to grey to green and hosts disseminated pyrite. A petrographic analysis in 1981 indicated the porphyry to be of trachyandesite composition. Fine-grained diabase dikes cut the porphyry, sometimes hosting minor pyrite. The southwest part of the intrusion is in fault contact with a chert pebble conglomerate and black shales of the Middle to Lower Jurassic Takwahoni Formation. This major fault trends northwest and truncates the southwestern edge of the porphyry intrusive.

Six mineralized zones have been outlined that contain veins of galena-sphalerite mineralization. The zones are defined by altered, recessive areas containing mineralized veins, between relatively unaltered walls of quartz feldspar porphyry. The zones appear to be offset by a left-lateral fault. Each zone contains at least one larger vein on the hangingwall side and often another vein on the footwall side. Smaller veins and veinlets, ranging from a few millimetres to 10 centimetres, cut the very altered quartz-feldspar porphyry that lies in the centre of the zone. The galena-sphalerite mineralization occurs as bands and disseminations within the veins. Minor pyrite and arsenopyrite are also present, as well as barren calcite veinlets.

The altered feldspar porphyry exhibits extensive manganese and limonite staining with carbonate alteration. The veins themselves, are silicified and host abundant limonite and carbonate. Several stages of deformation have occurred which include an early stage of brecciation and mylonitization followed by several periods of fracturing and veining. A petrographic analysis outlined the following events: 1) early quartz veining and silicification with the introduction of ore minerals; 2) calcite veinlets remobilized some of the ore minerals; 3) late chalcedony veinlets and some brecciation and fracturing resulted in an almost cataclastic fabric; 4) late-stage fracturing offset the stage 3 structures.

In 1981, chip samples taken across sphalerite-galena vein mineralization returned anomalous gold and silver values. One sample assayed 0.549 gram per tonne gold, 581.82 grams per tonne silver, 8.29 per cent lead, and 6.72 per cent zinc. Others assayed 0.34 gram per tonne gold, 205 grams per tonne silver, 3.46 per cent lead, 4.19 per cent zinc and 6.65 grams per tonne gold, 50.06 grams per tonne silver, 0.54 per cent lead, and 1.22 per cent zinc. Initial grab samples from the showing assayed 501.2 grams per tonne silver, 5.64 per cent lead, and 6.72 per cent zinc (Assessment Report 9824, part 2).

WORK HISTORY

The area was first staked in 1981 as the Griz 1-3 by Newex Syndicate with prospecting, mapping soil sampling and trenching completed in the same year. Newex collected 69 chip samples and 41 soil/talus samples and conducted mapping at various scales. Newex discovered six mineralized quartz veins zones within relatively unaltered feldspar porphyry at the Griz 3 showing (104K 114). The veins, where sampled, varied from 30-90 centimetres in width and up to 28 metres in length where visible.

In 1991, Omega Gold Corporation conducted a geochemical sampling program consisting of 79 rock samples, 47 soil samples and 7 silts on their A 1-8 claims which covered the Griz (104K 073), Griz 3 (104K 114) and Emu (104K 115) occurrences. At the Griz 3 showing samples were collected consisting of the fractured and brecciated porphyry which returned a maximum value of 200 parts per billion gold. This sample consisted of a 1 metre chip across sheared and fractured feldspar porphyry with strong manganese staining (Assessment Report 21908).

During 2016 through 2020, Brixton Metals Corporation expanded their Thorn property through staking and acquisition of claims including those covering all the Griz (104K 073), Tardis (104K 112), Griz 3 (104K 114) and Emu (104K 115) showings. Refer to Thorn (104K 031), Chivas (104K 180), East Outlaw (104K 083), Oban (104K 168), Trapper (Inlaw) (104K 078) and Metla (104K 161) for details of the work history of the greater Thorn property.

As of early 2021, no work had been done on the Griz (104K 073), Griz 3 (104K 114) and Emu (104K 115) since 1991 and the Tardis (104K 112) since 1987.

Bibliography
EMPR ASS RPT *9824, Part, 2;, *21908
EMPR EXPL 1981-128
GSC MAP 6-1960; *1262A
GSC MEM 362
Burrell, H., Deiss, A.M. (2021-06-23): Thorn Property NI 43-101 Technical Report Sutlahine River Area, British Columbia, Atlin Mining Division

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