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File Created: 24-Jul-85 by BC Geological Survey (BCGS)
Last Edit:  19-Jan-92 by Chris J. Rees(CRE)

Summary Help Help

NMI 092N8 Au1
BCGS Map 092N038
Status Developed Prospect NTS Map 092N08W
Latitude 51º 23' 42" N UTM 10 (NAD 83)
Longitude 124º 25' 45" W Northing 5694721
Easting 400572
Commodities Gold, Silver, Antimony, Copper, Zinc, Arsenic Deposit Types I05 : Polymetallic veins Ag-Pb-Zn+/-Au
Tectonic Belt Coast Crystalline Terrane Gambier, Plutonic Rocks
Capsule Geology

The Morris occurrence consists of several gold-silver-antimony- bearing quartz veins which have been explored intermittently since their discovery in 1907, although it has never been a producer. The area is in rugged terrain 6 kilometres south of the southern end of Tatlayoko Lake, and is accessible by road.

The Morris occurrence lies in the Gambier overlap assemblage, about 6 kilometres north of a large quartz diorite intrusion, the Tiedemann pluton, which forms the northeastern margin of the Jurassic to Tertiary Coast Plutonic Complex in this region. This pluton has an early Tertiary age of 63 million years, based on the potassium-argon method on biotite (Geological Survey of Canada Open File 1163, Map 1713A). The occurrence is within Lower Cretaceous sedimentary rocks with some interbedded volcanics, just north of a south-dipping thrust sheet comprising Upper Triassic rocks.

The gold and silver-bearing quartz veins are mainly hosted in folded and sheared mudstone, argillite, greywacke, sandstone, and minor quartzite, quartz-pebble conglomerate and limestone. In general the rocks strike east-southeast and dip moderately south. Sparse, disseminated pyrite is widespread. Quartz diorite intrusions are common; they are probably related to the Coast Plutonic Complex, and locally also host mineralized quartz veins. Numerous quartz-feldspar porphyry dykes, locally with argillic and limonitic alteration, cut the rocks but pre-date east-striking faults. Interbedded andesite and basalt occur within a kilometre to the northeast; they do not host the quartz veins of interest, but they do host copper mineralization covered by the Spokane occurrence (092N 001).

The mineralized quartz veins strike 320 to 350 degrees and dip 45 northeast. They show a spatial relationship with the quartz diorite intrusions, although most of the veins are actually hosted in the adjacent sedimentary rocks (Assessment Report 10520; Minister of Mines Annual Report 1935). Locally, the host rocks are silicified. The veins are not offset by the east-striking faults mentioned above, so they represent younger hydrothermal fracture-fillings. The youngest intrusions are basaltic dykes, one of which follows a quartz vein for 55 metres.

A notable feature of the veins is that they are rich in stibnite. In addition, the veins contain arsenopyrite, pyrite, minor chalcopyrite, sphalerite, and very rare bornite and chalcocite (Assessment Report 10520). The quartz gangue is commonly banded, and may have a cox-comb texture; calcite is rare. The gold is native, occurring in the quartz or as grains around sulphide minerals, primarily arsenopyrite (Assessment Report 10520). The tetrahedrite is probably the silver-bearing variety, and is also found as inclusions in sphalerite.

At least 4 major veins have been explored, partly underground (Assessment Report 10520; Minister of Mines Annual Reports 1921, 1935). The Number 1 vein has been traced on the surface for 260 metres, and has been drifted on underground for 187 metres. It averages 40 centimetres in thickness. Sulphides, mainly arsenopyrite, stibnite and pyrite, occur as lenses or stringers parallel to the vein walls. The average assay of 8 samples taken over a strike length of 95 metres and width of 40 centimetres was 18.5 grams per tonne gold, 252 grams per tonne silver, and 10 per cent antimony (Assessment Report 8320).

The Number 2 vein averages 20 centimetres in thickness and has been followed underground for 73 metres (Assessment Report 1663). Mineralization in this vein, and in the Number 4 vein, is similar to that in the Number 1 vein. The Number 3 vein, traceable for 30 metres on the surface, yielded a sample assaying 38 grams per tonne gold, 1060 grams per tonne silver, and 10 per cent antimony, over a 30 centimetre width (Assessment Report 10520).

Seven diamond-drill holes were completed in 1981 to test the Number 1 and Number 3 veins; several smaller veins were penetrated in the process (Assessment Report 10520). Sporadic mineralization in a variety of host rocks was encountered, with a wide range of gold and silver grades.

The high values of gold and silver at the Morris occurrence led to a program of bulk sampling and metallurgical tests. A 90 kilogram, composite bulk sample from Number 1 and Number 3 veins assayed 27 grams per tonne gold, 431 grams per tonne silver, 2.92 per cent antimony, and 4.92 per cent arsenic (Assessment Report 10520).

In 1966 it was estimated that based on a strike length of 104 metres, the Number 1 vein contained 19,000 tonnes of "ore" with an average grade of 10 grams per tonne gold, 110 grams per tonne silver, and 2.1 per cent antimony (Assessment Report 1663). In 1982 a reserve calculation was announced: this partly consisted of a summary of the bulk sampling referred to above, and also gave a provisional estimate of drill-indicated reserves of 172,000 tonnes grading 8.3 grams per tonne gold over an effective mining width of 4 metres (George Cross News Letter #116, 1982).

EMPR AR 1910-K156; 1916-K169; 1920-N214; *1921-G215; 1934-F12;  *1935-F29; 1937-F34; 1968-154
EMPR EXPL 1980-279; 1981-315; 1983-340
EMPR ASS RPT 1663, *8320, *10520, 11961
GSC OF 1163
GSC SUM RPT *1924A, pp. 59-73
GSC P 68-33, p. 87
GSC MAP 2063; 5-1968; 1713A
N MINER Jan.15, 1981
GCNL #166, 1982
EMR MIN BULL MR 223 B.C. 183