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File Created: 24-Jul-1985 by BC Geological Survey (BCGS)
Last Edit:  30-Oct-2014 by Laura deGroot (LDG)

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NMI 082M13 W1
Name DIMAC, SILENCE LAKE, GOTCHA, BOULDER Mining Division Kamloops
BCGS Map 082M082
Status Past Producer NTS Map 082M13E
Latitude 051º 50' 00'' UTM 11 (NAD 83)
Longitude 119º 41' 34'' Northing 5745930
Easting 314470
Commodities Tungsten, Wollastonite Deposit Types K05 : W skarn
K09 : Wollastonite skarn
Tectonic Belt Omineca Terrane Barkerville
Capsule Geology

The Dimac mine is located 4 kilometres north of Silence Lake, the open pit is on the west side of Maxwell Creek. The deposit was mined for tungsten during 1981 and 1982.

The area is underlain by northeast trending roof pendants in a granitic stock of probable Late Cretaceous or Early Tertiary age. The stock is probably related to the Cretaceous Raft batholith, 14 kilometres to the south. The stock intrudes northwest dipping metasediments of the Precambrian to Paleozoic(?) Shuswap Metamorphic Complex (Monashee gneiss) that have been isoclinally folded and regionally metamorphosed to amphibolite facies. Fracturing, shearing and alteration are evident in drill holes.

The property covers the area of contact between metasediments and a post-metamorphic stock with associated skarns. The metasediments consist of calcareous and noncalcareous biotite schist, biotite quartzite and skarn. The stock consists of biotite-quartz monzonite, quartz monzonite, granodiorite, quartz diorite and pegmatite. Contacts between the various rock types, and layering within them, trends northeast and dips northwest.

Calc-silicate adjacent to intrusive rocks has been altered to three major types of skarn: 1) the scheelite-bearing quartz-garnet- diopside-idocrase skarns 2) the scheelite and pyrrhotite-bearing quartz-garnet-actinolite-idocrase-diopside skarns and 3) the barren wollastonite-garnet-diopside-calcite skarns. Five northwest trending bands of skarn, of which three contain coarse-grained scheelite mineralization, occur over an area 50 by 120 metres. The northern band (band 1) strikes 050 degrees and dips 55 degrees northwest. In the vicinity of the open pit, two northeast trending metasedimentary screens, the `upper band' to the west and the `lower band' to the east, are engulfed in intrusive rocks. Skarn type 1 hosts economic mineralization in the `upper band', type 2 in the `lower band' and type 3 primarily in the `upper band' but also in the `lower band'.

The mineralization is primarily located along the intrusive contact of the quartz monzonite with the metasediments. A northwest trending, southeast dipping fault is interpreted to cut off the skarn bands to the north.

Skarn bands 1 and 3 may, respectively, represent the upper and lower limbs of an overturned, nearly isoclinal synform. Alternative- ly, bands 3 and 4 may represent a northeast plunging antiform related to the earlier isoclinal folding.

The mining operation exposed a 15 to 20 metre section of siliceous skarn containing up to 35 per cent wollastonite. Poor rock exposure along strike prevents detailed examination, but outcrops of wollastonite skarn were identified 170 metres south-southwest of the main showing.

In the pit, wollastonite occurs in calc-silicate zones which strike northeast and dip 60 to 70 degrees northwest. Individual beds are up to 100 centimetres across and consist of massive fresh-looking white wollastonite with fibres up to 3 centimetres long. Clusters of red-brown garnet, up to 6 centimetres across, commonly form 20 to 30 per cent of the total volume. Thin (10 to 100 centimetres) quartzite beds are intercalated with the calc-silicates. A sample analyzed by image analysis contained 75.9 per cent wollastonite (Open File 1991-17).

A total of 18350 tonnes of tungsten ore was produced from this deposit (Open File 1991-17). Indicated reserves of the stockpile are 1360 tonnes grading 1.5 per cent Wo3; indicated reserves in the open pit is 4535 tonnes grading 1.2 percent Wo3; indicated reserves of open pit material is 9071 tonnes grading 1.2 per cent Wo3; indicated reserves in the tailings pond are 18,142 tonnes grading 0.3 per cent Wo3; conversion used for all calculations is 1.2611 to obtain W (Filing Statement 21/84, Troudor Resources Inc.). The wollastonite potential has not been evaluated.

EMPR ASS RPT *4270, 5189, *7607, *7884, *15696
EMPR EXPL 1978-115,116; 1979-117; 1980-145,146
EMPR FIELDWORK 1978, pp. 93,94; 1988, pp. 493-495; 1991, pp. 247,248
EMPR GEM 1972-94; 1973-117,118
EMPR MAP 65, 1989
EMPR OF *1991-17; 1992-1; 1992-9; 1998-8-M, pp. 1-74
EMPR PF (Advance Drafting Ltd. (undated): Geology map showing DDH information; Elwell, J.P. (1978): Percussion Drilling Results and Preliminary Cost Study - Gotcha Property; Dickinson, R.A. and McClaren, M. (1978): Documentation Physical Work, Gotcha, Gotcha 2, Max 1 and Max 2; Ryan, B.D. (1979): A Report of Detailed Geological Mapping Program with Proposed Drill Program, Gotcha Tungsten Property; United Mineral Services Ltd. (1979): A Summary Report and Compilation of Data, Gotcha Tungsten Property; Dickinson, R.A. (1980-02-01): Diamond Drilling Summary Report: Gotcha, Gotcha 2, Gotcha 3 Claims; McDonald, J.D. (1981-04-29): Letter regarding Dimac Resources Corp. Silence Lake Tungsten Project small mine application; Prospectors Report 1994-57 by Horst Klassen)
EMR MP CORPFILE (Dimac Resource Corp.)
GSC MAP 48-1963
GSC OF 637
CMJ Oct. 1981
GCNL #241, 1977; #40, 1978; #50,#75, 1979; #163, 1981; #118,#139,
#172, 1982; #154, 1983
IPDM May/June 1984
MIN REV May/June 1983, p. 52
N MINER Sept.10, 1981; July 8,29, 1982; Jan.19, 1984
W MINER Oct. 1981