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File Created: 24-Jul-1985 by BC Geological Survey (BCGS)
Last Edit:  26-Sep-2012 by Karl A. Flower (KAF)

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NMI 094L3 Pb1
Name LINDA, WEST, JACKSTONE, GORF Mining Division Liard
BCGS Map 094L025
Status Prospect NTS Map 094L03E
Latitude 058º 12' 09'' UTM 09 (NAD 83)
Longitude 127º 09' 53'' Northing 6452724
Easting 607861
Commodities Lead, Silver, Zinc, Copper Deposit Types
Tectonic Belt Omineca Terrane Cassiar
Capsule Geology

This silver-lead-zinc prospect is situated in the upper reaches of Halls Creek, a small tributary west of Frog River, 19 kilometres northeast of Mount Irving in the Stikine Ranges of the Cassiar Mountains (Assessment Reports 16898, Figure 3; 20517, Figure 4).

The occurrence is in a northwest-trending belt of metasedimentary and minor metavolcanic rocks on the northeastern margin of the mid-Cretaceous Thudaka Batholith, possibly a faulted segment of the larger Cassiar Batholith (Geological Survey of Canada Paper 77-1A). The stratified rocks belong mostly to the Upper Proterozoic Ingenika Group of the Cassiar terrane; some Cambro-Ordovician units may be present as well (Geological Survey of Canada Maps 1712A, 1713A). They comprise calcareous and non-calcareous phyllites, schists, limestone and marble and minor greenstone (Geological Survey of Canada Map 42-1962). Metamorphic grade is up to greenschist facies.

In more detail, the property is underlain by chloritic phyllite or biotite-sericite schist, and micaceous quartzite of the Swannell Formation. Calcareous phyllite and carbonate of the overlying Tsaydiz Formation may also be present (Assessment Reports 2336, 16898, 20517). Coarse-grained biotite quartz monzonite and granodiorite of the Thudaka Batholith outcrops in the southwest of the property, with a steeply north dipping contact. Several quartz-porphyry dykes have been mapped and at least one basic to intermediate sill (Assessment Report 16898). The metasediments strike west or northwest, and dip moderately to the northeast or southwest, due to folding. One vertical, northwest-striking fault, and a steep, northeast-striking fault cut the property. The area of interest is centred around their intersection, covering about 1 square kilometre in the upper reaches of Halls Creek. This area has been mineralized, apparently accompanied by pyritic alteration and silicification; subsequent oxidation has produced conspicuous gossans and ferricrete.

Mineralization in the phyllite and quartzite occurs in lenses and fine stringers that are parallel or subparallel to the main fault structures. It consists of argentiferous galena, sphalerite, rhodonite, rhodochrosite and minor chalcopyrite and pyrolusite, in addition to the more widespread pyrite and pyrrhotite (Assessment Reports 2336, 16898). The more substantial sulphides may be massive or a mixture of sulphides and quartzite breccia. There is very little, if any, hydrothermal quartz or gangue quartz (Assessment Report 16898). Locally the galena is smeared out or crushed, indicating later faulting.

The main showings are located on areas of frost-heaved, mineralized boulders or float. Old trenches occur on the former Linda 9 claim (Assessment Report 2336), also designated the West 1 claim (Assessment Report 16898) and the Jackstone 1 claim (Assessment Report 20517). The best material is found in an area measuring 180 metres by 120 metres. A select grab sample was assayed at 13.22 per cent lead, 7.33 per cent zinc, and 120 grams per tonne silver (Assessment Report 2336). Early sampling by Conwest of the high grade float material, combined with more recent check sampling by Cominco, resulted in the following averages: 569 grams per tonne silver, 29.7 per cent lead, 6.8 per cent zinc and 0.6 per cent copper (Assessment Report 16898). Anomalous gold is also present. Trenching in these zones has revealed the mineralized bedrock, which has also been tested by a few diamond drill holes (Assessment Report 16898). Elsewhere on the property, sparse pyrite and galena occur in disseminations or in laminae in silicified sericite-biotite schist.

The northeast-trending (about 056 degrees) fault, probably the dominant structural control, is exposed in the creek in the north, and has similar mineralization, including a 2-metre thick capping of pyrolusite. The quartzite, grit and phyllite here are cut by fractures which are mineralized with galena, sphalerite, pyrite, rhodochrosite, rhodonite and minor chalcopyrite. High grade sulphides occur at fracture intersections. There is a reference to early work (done by Lake Expanse in 1952-1953) centred on this creek section, in which channel samples returned assays of 20.6 grams per tonne silver, 2.1 per cent lead and 1.3 per cent zinc over 8.2 metres, and 10.3 grams per tonne silver, 1.2 per cent lead and 0.7 per cent zinc over 87 metres (Assessment Report 16898). The channel samples appear to have been done along, not across, the mineralized fault.

In 1989, the area was staked by C. Graf as the Gorf property. In 1994, a program of geological mapping, stream silt sampling, rock sampling and prospecting was completed.

Bibliography
EMPR AR 1959-18; 1963-130
EMPR ASS RPT 467, *2336, 2995, 7523, 8549, *16898, 20517, 23774
EMPR EXPL 1979-270
EMPR GEM 1971-106
GSC MAP 42-1962; 1712A; 1713A
GSC P 77-1A, pp. 243-246

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