The Tip Top Zone is a 6-metre wide, 25-metre-long shear that contains gold, copper and silver mineralization. Schistose andesitic ash tuff (chloritic) and feldspar porphyry (sericitic) of the Lower Jurassic Hazelton Group are the host rocks.
Six trenches and several blastholes have been excavated by previous workers (prior to 1989 Calpine work) over a 200 metre by 50 metre area to improve exposure of the showing. This occurs as veins and pods of locally massive sulphides which have returned assays of up to 4.35 grams per tonne gold, 214.97 grams per tonne silver and 24.8 per cent copper from grab samples (Assessment Report 20030). A second style of mineralization was noted in the dacites, peripheral to the shear zone, which contained disseminated arsenopyrite. However, samples of this material assayed low gold values.
The main showing contains approximately 40 per cent massive sulphide veins, up to 40 centimetre wide, composed of up to 90 per cent chalcopyrite, 5 per cent pyrite, 5 per cent quartz-chlorite and trace covellite. Quartz veins compose 15 per cent of the mylonitic zone where it occurs. One 15 centimetre wide, 1.5 metre long quartz lens within this showing contains blebs of chalcopyrite (5 per cent), pyrite (2 per cent) and tetrahedrite (2 per cent) with possible tennantite, and abundant chlorite.
Work History
Little or no work has been recorded on the GNC claims prior to 1982, however much work has been done on the adjoining Tok, Ray and Sib claims which covered the Eskay mine (MINFILE 104B 008).
In 1982, Ryan Explorations carried out stream sediment sampling, some of which was on the later GNC claims. Several anomalous gold values were reported from streams draining the GNC claims.
An airborne geophysical survey (EM-VLF and magnetics) was flown over the GNC claims in early 1989 as part of a survey for Calpine Resources Inc. including other properties in the Eskay Creek area (Assessment Report 18964). A total of 514.7 kilometres was claimed by Calpine for the GNC property.
In 1989 a field program was conducted by Calpine Resource. Geological mapping at a scale of 1:2500 was undertaken as the grid cutting was in progress. The Porphyry and Tip Top zones were mapped in detail at a scale of 1:1000. A combined magnetometer and VLF-EM survey was implemented over 18.1 kilometres of cut grid. Selected test lines were also covered by an induced polarization survey, including the Porphyry zone which was given detail coverage at 50 metre line spacings. The total IP coverage amounted to 12.5 line kilometres. Soil sampling (1262 samples) was conducted over the cut lines with samples collected at 25 metre, and 12.5 metre intervals over the detail grids. In 1993, Homestake drilled one hole on the GNC 1 at a UTM coordinate of about 409620 East, 6277200 North in order to test for Eskay Creek, 21B style mineralization. Drilling during 1991 and 1992 on this area (the McKay West Target) defined an anomalous area with gold, zinc, antimony and arsenic values in mudstone near the top of the rhyolite. No potentially economic concentrations of base or precious metals were intersected in Hole 93-33 (Assessment Report 23193).
It appears that at some point, soon after 1993, the GNC 1-3, IKS 1 and several other Tok and Kay claims became permanent lots attached to the Eskay Creek mine (MINFILE 104B 008).
In 2019, Skeena Resources completed a minor prospecting and sampling program on the area as part of the Eskay Creek project. Three grab samples from the Tip Top occurrence area yielded from 1.8 to 8.8 grams per tonne gold and 5 to 144 grams per tonne silver (SRK Consulting (Canada), Inc. [2021-05-21]: Independent Technical Report on the Eskay Creek Au-Ag Project, Canada). The following year, a three-dimensional resistivity and induced polarization survey was completed on the property.
