The Ecstall occurrence is located on the Ecstall River about 70 kilometres southeast of Prince Rupert. Red Gulch Creek, a southerly flowing tributary, exposed the mineralization for a distance of about 610 metres between elevations of about 60 to 200 metres.
The Ecstall deposit, and a cluster of three spatially associated showings; the Third Outcrop (103H 012), the East Plateau (103H 050) and the Trench (103H 051), lie within the Scotia-Quaal metamorphic belt, which extends from Hawkesbury Island north to Work Channel. The belt consists of a Proterozoic(?)-Paleozoic metasedimentary and metavolcanic sequence that includes the Middle Devonian Big Falls orthogneiss, Early Jurassic orthogneiss, and Jurassic or Cretaceous mafic and ultramafic intrusive rocks. The assemblage may be correlative with the Nisling terrane. The metamorphic belt is intruded by the Late Cretaceous Ecstall pluton on the west, and the Paleogene Quottoon plutons to the east.
The rocks dip about 80 degrees east and consist of quartz-biotite-chlorite schists, quartz-hornblende-chlorite schist, quartzite grading to quartz-mica schist, minor black argillite and granitic gneiss. The volcanogenic massive sulphides in the Ecstall Belt are part of a mid-Devonian volcanic and intrusive event (Fieldwork 2000, pages 269-278). The quartz diorite gives a minimum age to the volcanogenic massive sulphides. A felsic metavolcanic associated with the deposit gives 393 Ma and the Big Falls tonalite gives 385 Ma. These are indistinguishable in age at stated accuracies. Of interest are local quartzites with detrital zircons of Precambrian age (Fieldwork 2000, pages 269-278).
The Ecstall deposit occurs in a hydrothermally altered sequence of volcanic/volcaniclastic rocks, close to a felsic volcanic centre. Two tabular concordant bodies, known as the North Lens and South Lens, have an en echelon relationship. Mineralization consists largely of pyrite with minor chalcopyrite and sphalerite and lesser pyrrhotite, marcasite and galena.
The North Lens measures about 300 by 150 by 30 metres and the South Lens measures about 400 by 360 by 7 metres. A 6.1-metre sample of the South Lens assayed 3.02 per cent zinc, 0.18 per cent copper, 20.6 grams per tonne silver and 0.69 gram per tonne gold (Minister of Mines Annual Report 1952).
The two lenticular bodies of massive pyrite strike north, dip steeply east and plunge steeply south. The North Lens contains 3.1 million tonnes grading 0.80 per cent copper, 2.0 per cent zinc, 43.5 per cent iron, 49.5 per cent sulphur, 17.1 grams per tonne silver and 0.5 gram per tonne gold. The South Lens contains 3.8 million tonnes grading 0.5 per cent copper, 3.0 per cent zinc, 41.3 per cent iron and 47.6 per cent sulphur. The upper 1.3 million tonnes grades 20.2 grams per tonne silver and 0.5 gram per tonne gold (Assessment Report 15488). Unclassified reserves in 1993 for the Ecstall deposit (North and South lenses) are 6,349,700 tonnes grading 0.6 per cent copper, 2.5 per cent zinc, 0.5 gram per tonne gold and 20.0 grams per tonne silver (George Cross News Letter No.26 (February 8), 1994).
A smaller deposit occurs 760 metres north of the North Lens, where 30 by 2.4 metres of massive pyrite is exposed.
Results of property-scale exploration by Falconbridge in 1986-87 indicated the presence of significant stockwork copper mineralization in felsic rocks, occurring south of the Ecstall River in Thirteen Creek area. The stockwork mineralization was interpreted as a possible feeder zone to a volcanogenic massive sulphide deposit. This area was explored by Atna Resources Ltd. in 1994, confirming stockwork copper mineralization and outlining disseminated copper mineralization over a large area, including a previously unexplored area at the north end of the grid. The work by Atna outlined disseminated and vein copper mineralization over a 2000 by 150 metre area on Thirteen Creek grid. Results of a systematic chip sampling program across the zone yielded values of 0.198 per cent copper over 124 metres across one of the better exposures (Assessment Report 24605).
Seasoned gold prospector Charles Todd discovered the Ecstall massive sulphide deposit in 1890 (Flewin, 1924, page 209). His financial partner was J.N. MacKay, chief factor for the Hudson’s Bay Company at Port Simpson. While no credit is given to local natives, Todd was the Indian Agent for northern British Columbia at the time of this discovery, and was likely guided to this remote, heavily overgrown site. One sample of Ecstall sulphides reached the Geological Survey of Canada laboratory in Ottawa in 1891.It is described by G.C. Hoffman (1892, p.67R) as: “12. PYRITE. A crystalline, granular, massive, iron-pyrites, through which is disseminated a trifling amount of blende, occurs at the head of Eckstall Inlet, south of Port Essington, Skeena River, British Columbia, where it is said to constitute a vein fifteen feet wide, nearly vertical, running in a north-easterly direction from the shore and traceable for nearly a mile. It has been examined by Mr. Johnston and found to contain a trace of gold and 0.350 of an ounce of silver to the ton of 2,000 lbs., likewise a trace of copper and a little zinc, but no nickel or cobalt.”
Todd decided not to stake the Ecstall showing, presumably reflecting his interest in gold prospects.
The Ecstall deposit remained open for 10 years and was finally staked for the first time in April, 1900 by prospector Henry Prevost for William Edgar Oliver of Victoria. The four initial claims, Bell-Helen, Bluestone, Red Bluff and Red Gulch were sold to John Bryden that same year (Minister of Mines Annual Report 1901, pages 788-789), and the claims were Crown granted in 1902. Table 3 in the Annual Report summarizes the history of ownership and exploration at the Ecstall deposit. Although most often referred to as the Ecstall deposit it has also been called the Ecstall River deposit and the Red Gulch deposit. The latter name was taken from the deeply incised creek that exposes the massive sulphides.
The outcrops of the North and South lenses cannot be accessed from the air due to the tight canyon and heavy vegetation. On a bright day, glimpses of the North Lens sulphides are possible from a helicopter maneuvering in this confined space. As of 2000, it was still possible to land Jet Ranger and Hughes 500 helicopters in the clearing at the main portal, just west of Red Gulch Creek.
During the first half of the 20th century, access to most spectacular sulphide exposures of the North Lens was possible using a well-built trail high up along the west bank or a similar trail at lower elevation along the east bank (Mason, 1940). By 1940, access to the North Lens exposures was facilitated by traveling along the main adit then up a series of raises and a manway to small, near-vertical shaft entrance just on the west side of the Red Gulch Creek, just northwest of the northernmost limit of the North Lens. In 2000, sections of the trails high up on the west and east banks still survived, however, erosion down the many steep drainages that cross these trails had sluiced all overburden away, exposing steeply inclined, wet, mossy bedrock that must be avoided. With the underground portal blocked by a collapse, the only remaining route to all the sulphide exposures of the Ecstall deposit is along the floor of the canyon. Successful visitors describe this route as “arduous” and “harrowing”.
Before setting out, ensure you have thick leather gloves; rubber caulked boots are also strongly recommended – both these items are readily available in Terrace or Prince Rupert. The traverse northward can start on either bank of Red Gulch Creek as it enters the canyon. By the time you reach the small (1 metre high) waterfall across the creek that is just south of the Dunsmuir adit, you must keep to the east edge of the creek for the rest of the journey. The main obstacle to progress is a series of steep bedrock ribs that jut out of the east bank, forcing hikers into the rapids and deep-water pools of the creek or forcing them to climb up the east bank to find a low point along the rib where it can be crossed safely. As soon as each rib is cleared, climb back down to the edge of the creek for the next section of northward progress. This will also provide opportunities to cross over to the west bank of the creek to view the outcropping sulphides of the South Lens, but always return to the east bank before heading northward again. There will be several ribs to overcome and the climb back down to creek level is usually the most difficult part. By the time you are 200 metres downstream from the main waterfall, which is 115 feet or 35 metres high, you are standing at the base of the bank directly downslope from two old adits that access exposures of the North Lens sulphide deposit; at this location, exposed sulphides of the South Lens are visible on the west bank of the creek. In the bush, search for old steel cables that are secured high up the bank. Using your leather gloves, climb up a cable which will allow you to safely reach the east bank of the creek above the main falls. Continue north along the east bank of the creek for another 200 metres until you reach the main exposure of the North Lens sulphides in the creek.
The geology at the Ecstall deposit has been described in reports by Peatfield (1995, 1988), Schmidt (1995a), Birkeland (1994), Hassard et al. (1987b), Douglas (1953), Bacon (1952), Holyk (1952a) and MacDonald (1918, 1927) and is illustrated in maps by Schmidt (Figure 4 in 1995a), Hassard et al. (Figure 6 in 1987b), Douglas (1953), Bacon (1952, page A83) and Holyk (1952b,c). Bacon’s published map is a 1:1-scale tracing of Holyk’s unpublished geology map.
The Ecstall deposit consists of two en echelon sulphide lenses, the North Lens and South Lens. These two lenses are exposed discontinuously for 570 metres along the banks of Red Gulch Creek. The two deposits strike north, dip 80 degrees east and plunge 70 degrees to the south. The North Lens is considerably larger and reaches a maximum width of 37 metres near its northern end. The North Lens has been completely delineated by drilling, but the South Lens remains open to the south and to depth.
The Ecstall deposit is best exposed in a spectacular outcrop of the North Lens in the floor of a narrow canyon just upstream from the main waterfall. Seasonal floodwaters of Red Gulch Creek have exposed a continuous outcrop of faintly laminated, medium to coarse-grained pyrite over a 25 by 90 metre area on the east side of the creek, 1.5 kilometres upstream from its junction with the Ecstall River. This is the northernmost outcrop of the deposit.
Both the North and South lenses are composed of medium to coarse grained granular pyrite with trace to minor sphalerite and chalcopyrite, and rare galena and pyrrhotite. The sulphides are cemented by less resistant calcite-quartz-sericite gangue which preferentially weathers out, freeing the sulphide grains. All outcrops of the Ecstall deposit massive sulphides break down rapidly and do not form major gossans. An unusual consequence is that sections of the North Lens exposed along the creek are blanketed by `sand banks’ of bright pyrite. Similar accumulations of fresh pyrite sand banks have been built up by back eddies all the way down Red Gulch Creek. The stream bed along the lower few hundred metres of Red Gulch Creek is strongly hematitic. The large sandbar that forms where Red Gulch Creek joins the Ecstall River is similarly `painted’ with a thick coating of hematite. This prominent sandbar probably first drew the First Nations to this site and up Red Gulch Creek for supplies of ochre.
The two massive sulphide lenses are enveloped by a one- to two-metre-thick zone of quartz-muscovite/sericite schist. Schmidt (1995a, page 9) documented that the footwall strata west of the South Lens and the hangingwall strata east of the North Lens are mirror-image sequences consisting of quartz-muscovite schist, quartz-muscovite biotite gneiss, quartz-chlorite schist and a unit of interlayered muscovite and chlorite schists. He concluded that the two main lenses of the Ecstall deposit lie in opposite limbs of a tightly folded antiform and that the fold axis is near-horizontal and located above the present erosion surface. Douglas (1953a) noted that the lenses diverge at depth.
A distinctive sill-like body of foliated hornblende-quartz-feldspar quartz-diorite rock intrudes the hangingwall strata. Childe (1997, pages 222-227) obtained a U-Pb age of 377 +9/-4 Ma from this rock, within analytical error of Gareau’s U-Pb age of 385 +/-4 Ma for the Big Falls tonalite, suggesting that the two foliated intrusions are comagmatic.
Base metal sulphides show zonal distributions through the deposit. Sphalerite content increases in a narrow zone along the eastern (hangingwall) contact of the North Lens. Chalcopyrite is significantly enriched along the footwall of the North Lens, and a reserve has been calculated for this large block of the North Lens footwall that grades nearly 2.0 per cent copper. The upper section of the South Lens (that is, the portion of the lens lying above an elevation of 35 metres below sea level) has copper grades three times greater than the deeper section of the same lens, but zinc content is constant throughout.
In plan, the outline of the North Lens resembles a tadpole; the northern end of the deposit is consistently the thickest part at all levels. In long section, the North Lens has the outline of a heraldic shield. The maximum dimensions of this sulphide body are 333 metres long by 150 metres deep by 37 metres wide. The deposit has been drilled off, although the potential still exists for separate en echelon lenses nearby. The western, footwall section of the North Lens includes a copper-rich zone of 385,000 tonnes grading 1.85 per cent copper, 18 grams per tonne silver and 1.0 grams per tonne gold (Mason, 1940f). A thin zinc-rich band has been identified along the eastern contact at the northern end of the lens. In 1940, five channel samples across the entire North Lens were collected from underground and analysed for nine elements at the Texas Gulf Sulphur Company laboratory (Mason, 1940c). Selenium analyses ranged from 40 to 100 parts per million (ppm). In the present study, four surface samples of North Lens sulphides were analysed for 39 elements; selenium concentrations ranged from 31 to 108 ppm.
The South Lens is a thin sulphide slab. This lens thickens slightly below its surface exposure and the grade increases, then drops off again at depths below 35 metres below sea level. The South Lens has a maximum length of 533.4 metres along strike and a maximum thickness of 15.25 metres. It has been intersected in drilling at a depth of 293 metres below sea level, and no holes test the zone below that level. In long section, the South Lens resembles a parallelogram with one horizontal edge (the present erosion surface) and two roughly parallel edges plunging southward at 70 degrees. The South Lens remains open to depth at its southern end and along strike further to the south. The geological resource for the South Lens is 3.8 million tonnes at 0.44 per cent copper and 2.95 per cent zinc (Douglas, 1952).
Two sulphide lenses lie just to the east and uphill of the North Lens. Both are small, but significant, because they indicate potential for additional sulphide lenses to the east of the North Lens, perhaps stepped off in an en echelon pattern. Sixty-five metres north-northeast of the main waterfall in Red Gulch Creek, the East Lens crops out just seven metres east of the North Lens, separated from it by a unit of black argillite (Schmidt, 1995, Figure 4). Early geology maps depict the East Lens as one sulphide body, but Schmidt shows that the East Lens consists of two adjacent thin massive pyrite layers exposed in the canyon of a small creek that drains southwestward into Red Gulch Creek.
The Five Foot Vein (Douglas, 1953, pages 20-21) is another massive pyrite lens that lies east of the North Lens, 80 metres southeast of the main waterfall in Red Gulch Creek. It crops out at 160 metres elevation, in a small creek that drains into Red Gulch Creek at the southern end of the North Lens (Figure 4 in Schmidt, 1995a). A grab sample collected by Schmidt (sample US-E94-013 on Figure 5 in Schmidt, 1995a) assayed 1.38 per cent copper, 0.27 per cent zinc, 54.5 grams per tonne silver and 280 parts per billion (ppb) gold.
One massive sulphide lens has been identified on the west side of the deposit. The Southwest Shear (Douglas, 1953, pages 21 and 28) crops out uphill and to the west of the South Lens, 120 metres south-southwest of the portal of the Dunsmuir Tunnel, as a 25-centimetre-wide band of massive pyrite, hosted in quartz-sericite schist. Directly south, just north of the old mining camp and 140 metres east of the Main Adit portal, this horizon is exposed again in a large open cut near the base of the hill (Hassard et al., 1987b, Figure 6), where it is termed the Trench prospect (103H 051). The sulphide bed is 10 centimetre wide in this location, again hosted in quartz-sericite schist, and a sample assayed 330 ppm copper, 1200 ppm zinc, 46 ppm lead, 4.5 ppm silver and 70 ppb gold (Hassard et al., 1987b, page 26). This same zone was intersected in the Main Adit, mid-way between the portal and the No. 1 crosscut, and was also intersected in underground drillholes 60 and 60a, drilled southward from the east end of the No.1 crosscut. The Southwest Shear/Trench prospect is significant because it indicates good potential for a lens of massive sulphide mineralization en echelon to the southwest of the South Lens.
Further to the north and south of the Ecstall deposit, good potential for additional massive sulphide deposits along the Ecstall horizon is indicated by the Third Outcrop (103H 012) and West Marmot (103H 081) prospects to the north, and the North Mariposite (103H 052) and Mariposite (103H 052) prospects to the south.
The Ecstall deposit has been evaluated at different times as a possible source of pyrite (for sulphuric acid production), copper and zinc; consequently several reserve calculations have been completed. The global resource for the deposit is 7,279,327 tonnes at 0.55 per cent copper, 2.75 per cent zinc, 17 grams per tonne silver and 0.5 gram per tonne gold (Tipple, 1958).
The Ecstall deposit has been accessed from underground at five locations. In 1901, three short adits and a three-metre-deep shaft were completed (Flewin, 1902). The Dunsmuir Tunnel, a 21-metre crosscut tunnel, was collared at 90 metres elevation, just below the southernmost outcrop of the South Lens. Track for a tramway was laid from Dunsmuir tunnel 1006 metres to the wharf constructed on the north side of the Ecstall River. This adit allowed bulk sampling of the South Lens from two short (7 metres each) drifts blasted to the north and south of the main tunnel along the massive sulphide lens. During this same period, two short adits were collared at 145 and 155 metres elevation on the southern part of the North Lens, 200 metres east of the big waterfall in Red Gulch Creek (see Figure 4 in Schmidt, 1995a) and another short adit was collared into the base of the hillside at the campsite. The location of the 3-metre-deep shaft is unknown.
The Main Adit system was developed between 1938 and 1940, collared at 37 metres elevation on the alluvial fan to the southwest of the deposit, and just west of the point where Red Gulch Creek emerges from its canyon. This network of underground workings totals 1250 metres in length, consisting of a main drift (847 metres) along the footwall of the deposits, seven crosscuts (totalling 220 metres) off the main drift, one raise to surface (183 metres) at the north end of the drift, and three short exploration levels (drill stations) off this raise. The main portal collapsed decades ago and the condition of the rest of the underground workings is unknown.
Nine diamond drill programs have been completed at the Ecstall deposit. A total of 8265 metres of drilling have been completed in 98 surface and underground holes.
Structural Analysis of the Ecstall Volcanogenic Massive Sulphide Deposit:
Macdonald (1917, 1918, 1920, 1927) envisaged the two lenses of the Ecstall deposit as a two separate sulphide bodies emplaced within a single shear zone. In 1918 (pages 13-14) he considered that the two lenses might be pieces of a single longer sulphide lens wrenched apart along a sub-parallel fault. Holyk (1952a) concluded that the two sulphide lenses formed within two parallel, north-trending shear zones. As a consequence he named them the east shear, which hosted the North Lens, and the west shear, which hosted the South Lens. He also proposed that these two parallel shears likely merged together at some higher elevation, now eroded away, so that the two mineralized shears formed as splays off a single larger structure.
Bacon (1952) concluded that the two main sulphide lenses must be separate bodies lying within parallel shear zones after rejecting the concept that there might be a steeply-plunging pair of isoclinal anticline-syncline fold axes between these two lenses that pulled the South Lens into en echelon position with the North Lens. Similarly, Douglas (1953) also concluded that the closely-spaced North and South lenses were unconnected ore deposits. However, he did observe a crumpled or crenulated chlorite schist unit that separates the two lenses, and suggested that this intense foliation might represent axial plane cleavage. Secondly, he recognized that, since the sulphides of the Trench (31), the South Lens and the North Lens form an en echelon array, they might have formed in a geometric array as a result of a single, linked process. Finally, Douglas recognized the northern end of the exposed North Lens sulphides represented a tight, isoclinal fold.
Peatfield (1988) was the first worker on the property to recognize the Ecstall deposit as an exhalative volcanic-hosted massive sulphide deposit. Hassard et al. (1987b) regarded both sulphide lenses as similar south-plunging `blades’ of sulphides, and concluded that the North Lens was a tightly-folded, south-plunging antiform, whereas Douglas’ interpretation saw the North Lens sulphides as a south-plunging synform.
The current interpretation of the structural setting for the Ecstall ore deposits has grown out of the conclusions from three studies.
Following detailed mapping of the area of the two deposits, Schmidt (1995) concluded “the two lenses lie in opposite limbs of a tightly folded, overturned, steeply east-dipping antiform. The sulphide lenses diverge at depth and no fold closures have been found in the map area, suggesting the fold axis is horizontal or dipping at a low angle and the fold hinge was located above the present erosion surface along Red Gulch Creek”. This revolutionary interpretation is supported by the observations that a thin, but extensive body of foliated granodiorite or biotite-quartz-feldspar gneiss that trends along the hangingwall of the North Lens, also occurs as discontinuous pods within the footwall strata of the South Lens (Schmidt, 1995). Peatfield (1995) observes that metal ratio zoning in the two lenses suggests that they face in opposite directions. Given this geometry it is likely that the Five-Foot Vein (34) and the Trench Zone (31) are repetitions of the same sulphide zone exposed on opposite limbs of this same anticlinal fold.
From separate studies, based on data collected in different areas, Gareau (1991c, pages 875-876) and Gallagher (Alldrick and Gallagher, 2000, pages 259-261) both conclude that strata in the Ecstall belt record two separate episodes of isoclinal folding.
From separate studies, based on data collected in different areas, Schmidt (1995, Photo 9) and Gallagher (Alldrick and Gallagher, 2000, page 261) both recognize near-vertical stretching lineations in breccias and conglomerates. The amount of stretching was estimated at 10:1 and 8:1, respectively.
Like all pre-Cretaceous rock strata of the region, the two sulphide lenses of the Ecstall deposit – and all other mineral deposits of the belt - have been subjected to two episodes of regional metamorphism that included intense compression and isoclinal folding. As a result of the first metamorphic episode, the originally roughly equidimensional sulphide lens would be compressed into a much thinner and elongated lens in the direction of least compressive stress. If sufficiently elongate, this lens would wrap around a local isoclinal fold axis, with the thinned sulphide layer draped down both limbs of the isoclinal fold (Figure Xb). This folded sulphide ribbon would have a thickened lobe of sulphides accumulated in the lower stress region of the fold axis, and in the case of this deposit, during the process of recrystallization of all the sulphide minerals, chalcopyrite has preferentially accumulated there in the interstitial spaces between the equant pyrite grains.
The second metamorphic episode refolds this thinned, isoclinally folded lens a second time, thinning the sulphide layer further, elongating the sulphide layer along the fold limbs further, and wrapping the already doubled sulphide layer over another (F2) fold axis, so that there is now four layers of ultra-thinned, ultra-elongated sulphides. Where compression and attenuation along the fold limbs is sufficiently great, incorporated wall rock (originally footwall and hangingwall lithologies) are preserved as apparent `selvages’ or layers of country rock or gangue that are now interpreted as intermittent accumulations of volcanic ash during a hiatus in the accumulation of the exhalative sulphides. MacDonald (1918, pages 14-15) describes and illustrates the `East Lens’ which may be a relict of the second limb of sulphides preserved close to but separate from the main mass of the North Lens. Following this second phase of isoclinal folding, the outline of the sulphide lens in long-section resembles a pair of `pant-legs’.
A final deformation event recorded in the sulphide lenses of the Ecstall deposit is the pronounced near-vertical stretching of all rocks of the area that accompanied the upward emplacement of the partially crystallized Ecstall Pluton in mid-Cretaceous time (93 Ma). This process dramatically stretched cobbles in conglomeratic rocks and equant clasts within coarse breccias into 10:1 and 8:1 length-to-width ratios, respectively, and also affected the twice-deformed sulphide lenses of the Ecstall Belt, imparting vertical stretching, so that the profile of the North Lens was altered from an orthogonal outline to a diamond shape, resembling an heraldic shield.
Recent erosion along Red Gulch creek exposed the Ecstall ore deposit, but also removed much of the sulphide lens, and in particular the F2 fold hinge, so that the remaining exposure now resembles two separate sulphide layers. Reconstruction of the pre-erosion deposit indicates that the original single lens was roughly 13 million tonnes.
Exploration Challenges at the Ecstall Volcanogenic Massive Sulphide Deposit:
The complex geometry of the Ecstall North and South sulphide lenses puzzled all exploration teams working on the deposit. Especially frustrating were the abrupt termination of the north end of the North Lens, just as the sulphide lens thickened dramatically and copper grades increased. Through the course of many holes drilled into this small area, geologists also noted that the enveloping sericite schist rocks also terminated abruptly, and that foliation directions were highly irregular in this area, suggesting that the schists were `wrapped around’ the bulge of sulphides at the north end of the North Lens. A further frustration was that holes collared in the one location along the deposit where drill intersections of sulphides appeared to be a certainty – drilling in the `central’ section where the two en echelon lenses overlapped – drillholes consistently failed to intersect any sulphides at all.
Development of a structural history that accounted for the observed features would have facilitated the exploration of the deposit, reducing the numbers of holes drilled through unmineralised zones and optimizing all other drilling. The point to stress, is that this latest structural interpretation was built upon extensive structural and stratigraphic observations made by a series of geologists (Gareau, Schmidt, Gallagher), all examining the country-rock strata – it is unlikely that a coherent explanation for the current geometry of the Ecstall deposits could have be deduced from studies of the sulphide deposits alone.
The structural history and structural fabric is a region-wide phenomenon. Many other sulphide lenses within the Ecstall Belt record the same events and display similar structural geometries. This is clearly demonstrated by the distribution of four en echelon sulphide lenses at the Packsack deposit (103H 013), and likely applies to sulphide lenses exposed at the Horsefly (103H 014), Five Foot Vein, Trench and Third Outcrop sulphide lenses as well. Fitting this new structural interpretation and geometry to these occurrences helps us assess whether past drilling was effectively located, and may reveal new, optimum drill targets.
The Scotia (103I 007) massive sulphide deposit lies within a separate roof pendant of strata that is perched on top of the Ecstall pluton. The original geometry of this deformed deposit may have resembled the Ecstall deposit geometry, but Scotia is likely now substantially rotated, and possibly further deformed. Also, it will not display any effects of the late stretching episode since its host strata do not lie laterally outboard of the Ecstall pluton.
On the Ecstall South Lens, the UTM location marks the midpoint of the outcrop area of the South Lens of the Ecstall volcanogenic massive sulphide deposit. The South Lens is physically separate from the Ecstall North Lens; the two deposits have an en echelon relationship in outcrop. However, since the North and South Lenses are interpreted to be erosional remnants of a single, much larger, sulphide deposit, the South Lens is described in detail in the preceding section about the Ecstall North Lens.
The showings were apparently discovered by First Nations residents of the area, and staked in the 1890s by Charles Todd, Indian Agent for northern British Columbia for himself and J.N. MacKay, Hudson's Bay Company Chief Factor at Fort Simpson. Four claims, the Bluestone, Bell Helen, Red Gulch, and Red Bluff were staked on the showings. John Bryden and associates of Victoria purchased the property in 1900 and in March 1901 incorporated The British Columbia Pyrites Company, Limited. The above four claims and the Queen claim (Lots 111-115, respectively) were Crown granted to the company in 1902. Underground work was begun in 1901. A crosscut adit was driven 20 metres to the mineralized zone and drifts totalling about 12 metres were run to the north and south. Diamond drilling totalled 21 metres. A tramline was built 720 metres to the river in 1902. A bulk sample of about 90 tonnes from the mineralized zone was shipped to the Victoria Chemical Works, probably in 1903.
No further activity was reported until late in 1916 when the property was optioned to New York agents for The Granby Consolidated Mining, Smelting and Power Company, Limited. Diamond drilling by the company during the period 1917-1920 totalled about 3350 metres. The option was given up in the summer of 1920. Granby optioned the property again in 1923. Further diamond drilling and metallurgical studies were reported. The option was given up later in the year and the property reverted to British Columbia Pyrites. Based on diamond drilling to that date the two main mineralized lenses were indicated to contain about 4,536,000 tonnes averaging 49.35 per cent sulphur, 42.75 per cent iron, 0.2 per cent lead, 2.30 per cent zinc, 0.80 per cent copper, 0.69 gram per tonne gold and 24.3 grams per tonne silver. Included in the above is a section in the west part of the North Lens containing an indicated 589,670 tonnes averaging 1.91 per cent copper, 2.30 per cent zinc, 1.0 gram per tonne gold and 34 grams per tonne silver (W.B. Maxwell 16/04/1942 - for Metals Controller - British Columbia Pyrites Company, Limited).
The Sulphide group of 16 claims (Lots 2661-2676) were staked surrounding the original group and extending south across the Ecstall River; the dates of staking and Crown granting are not available.
Texas Gulf Sulphur Company purchased the property from British Columbia Pyrites in 1937. A geophysical survey was carried out and some diamond drilling was done to check prior work. An operating company Northern Pyrites, Limited was incorporated in December 1937. A new crosscut adit was begun on the west side of Red Gulch creek at about the 30-metre elevation in 1938. The adit was extended to a length of 847 metres in 1940. Seven crosscuts totalling 263 metres were driven across the mineralized zone from the adit and a 60 degree raise was driven about 180 metres to the surface.
The property was transferred to another Texas Gulf subsidiary, Sulgas Properties Ltd., which was incorporated in 1951; Northern Pyrites, Limited was wound up voluntarily in 1952. During 1952, Sulgas carried out 420 metres of surface diamond drilling, 2707 metres of underground diamond drilling, and a low frequency electromagnetic survey. Reserves were reported to be at least 8,000,000 tons, no grade stated (Bulletin 39, page 41, 1957).
The assets of Ecstall Mining Company Ltd. were transferred to the parent company, Texas Gulf Sulphur Company, in 1960 and Ecstall was placed in voluntarily liquidation in August of that year. In 1966, a 10-ton bulk sample was shipped for metallurgical testing.
The company name (Texas Gulf) was changed in 1972 to Texas Gulf, Inc., and in 1973 to Texasgulf Inc. A horizontal loop electromagnetic (EM) survey was carried out over 8.7 line kilometres covering Jungle 101 claim (units 1-3, 14-19) in 1975. Texas Gulf back in 1965 incorporated a new subsidiary Ecstall Mining Limited to hold the property; the latter name was changed in 1975 to Texasgulf Canada Ltd. This company was acquired in 1981 by Canada Development Corporation, at that time 87.7 per cent owned by the Government of Canada. The name (Texasgulf Canada) was changed in 1981 to Kidd Creek Mines Ltd. They dropped the claims and they were re-staked by Mr. C.W. Graf. In 1981, the property was optioned by a joint venture of E & B Explorations Inc. and Welcome North Mines Ltd. who did airborne geophysics, geology and geochemistry. After the property was dropped, Noranda Exploration Company Limited optioned the property in 1985. They staked more claims and carried out airborne EM surveys, ground geophysics, geology and rock geochemistry. Noranda dropped the property in 1987 and the claims were transferred to Mr. Graf. In 1988, Ecstall Mining Corporation purchased the property consisting of 15 claims including Ecstall 8, 9, 10, 15; Tall 1, 3, 6, 13; Fall 10-11 and Fall 12-13 Fr. In 1989, Cominco Ltd. optioned the deposit.