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File Created: 24-Jul-1985 by BC Geological Survey (BCGS)
Last Edit:  24-Jun-2013 by George Owsiacki (GO)

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NMI 104J5 Cu1
Name MINERAL HILL, PET, KETCHUM LAKE Mining Division Atlin
BCGS Map 104J032
Status Prospect NTS Map 104J05W
Latitude 058º 23' 55'' UTM 09 (NAD 83)
Longitude 131º 47' 13'' Northing 6476465
Easting 337130
Commodities Copper, Zinc, Gold, Silver Deposit Types L03 : Alkalic porphyry Cu-Au
Tectonic Belt Intermontane Terrane Plutonic Rocks, Stikine
Capsule Geology

Chalcopyrite-hematite mineralization occurs in a 243 by 91 metre area adjacent to the Old Telegraph Trail and the Dudidontu River, between Ketchum and Camp Island lakes, approximately 66 kilometres northwest of the community of Telegraph Creek (Assessment Report 4095).

The Pet or Mineral Hill occurrence area is underlain by extensively altered andesites of the Upper Triassic Stuhini Group and part of a large Late Triassic and Early Jurassic intrusion ranging in composition from granodiorite to syenite. The Mesozoic rocks are overlain by extensive Miocene to Pleistocene basalt flow rocks intercalated with minor rhyolite. Northeasterly and north to northwesterly trending fault systems are the dominant structural feature.

The main mineralized area is contained within granitic rocks that have been variously described as syenite, hybrid syenite and granodiorite. Thin section study and feldspar staining indicate the rock may be classified as a leucocratic, medium grained, hypidiomorphic-granular, biotite quartz monzonite or quartz-bearing monzonite.

The intrusive rocks are extensively fractured. Locally, strongly foliated rocks have developed along north trends and commonly contain narrow brecciated zones in which mineralization normally occurs.

The most widespread alteration is a pervasive, pink colouration that may be caused in part by potassium feldspar but is probably largely due to the presence of finely dispersed hematite. However, the most profound alteration is replacement and associated fracture filling by ankerite which may form 10 per cent or more of the rocks. Sheared rocks usually appear bleached due to an increase in sericite and clay minerals and an attendant destruction of biotite. A distinctive gossan has formed over parts of the mineralized zone characterized by "limonite" that is a dark yellowish brown colour. This was determined by X-ray to be an amorphous substance derived mainly from the alteration of ankerite.

Mineralization occurs in discontinuous, braided, breccia zones a few centimetres to a couple of metres in width. The strongest mineralization consists of coarse grained specular hematite containing random sulphide grains or, less commonly, patches of sulphide grains with little or no hematite. The most widespread mineralization is scattered grains or stringers of specular hematite and/or sulphides on fracture and shear planes or occasionally with calcite or quartz stringers. Detailed examination reveals that in addition to the main sulphides chalcopyrite and pyrite, small amounts of bornite, chalcocite, minor sphalerite, tennantite and traces of an unidentified sulphosalt are present. Some malachite, thin goethite rims on sulphide grains and fractures, and formation of minute covellite "flames" on bornite and chalcopyrite are also evident.

The majority of composite samples taken from the 243 by 91 metre mineralized area analysed at least 0.2 per cent copper (Assessment Report 4095, page 5). In 2006, a series of 12 mineralized grab and chip samples were collected from two trenches located in the west-central part of the Mineral Hill zone and results ranged from 0.86 to 5.03 per cent copper, 0.06 to 0.54 gram per tonne gold and 5.7 to 20.7 grams per tonne silver. Select mineralized samples assayed up to 8.68 per cent copper (Assessment Report 29276).

The Pet 1-91 and Pet 69 Fraction were held by Texas Gulf Sulphur Company. Exploration work carried out by the wholly owned subsidiary Ecstall Mining Limited during 1971-73 included reconnaissance geological mapping, geochemical and magnetometer surveys over 40 line kilometres, trenching on Pet 17, 19, 29, 37, and 39, and diamond drilling in two holes totalling 384 metres on Pet 19 and 37. The company name (Texas Gulf) was changed to Texas Gulf, Inc. in 1972 and to Texasgulf Inc. in April 1973. Texas Gulf discovered porphyry copper-gold mineralization as part of a regional reconnaissance program in 1971 and results of this work identified extensive copper-in-soil geochemical anomalies and a significant zone of copper-gold mineralization referred to as the Mineral Hill prospect. The Mineral Hill prospect consists of a north-trending zone measuring approximately 93 metres in width and 243 metres in length. The zone was defined by a series of twelve, 3.0 to 15.0 metre long, hand-excavated trenches. According to Texas Gulf all composite trench samples collected within this zone returned copper values ranging from 0.18 to 1.83 per cent copper along with elevated gold and silver values. Some sample intervals yielded values of up to 1.6 metres averaging 3.1 per cent copper. The geochemical surveys completed by Texas Gulf defined a copper-in-soil anomaly up to 400 metres in width that extends intermittently for approximately 3 kilometres along strike. In 2006, Panorama Resources Ltd. conducted a helicopter-borne magnetic survey that totalled 347 line kilometres, a program of geological work including digitizing the Texas Gulf data, preparing digital elevation models and detailed topographic maps, and collecting 12 rock chip and grab samples.

EMPR ASS RPT 3695, *4095, *29276, 30522
EMPR GEM 1971-49; *1972-549-551; 1973-512,513
EMPR PF (Drill logs, plan and section; 104J General File - Claim map 73M, Dec. 1970)
EMPR OF 1996-11
GSC OF 707
GSC MAP 9-1957; 21-1962; 1418A; 1712A; 1713A
GSC SUM RPT 1925, Part A, pp. 33A-99A
Falconbridge File