Post by
KnaveofDiamonds on Aug 02, 2023 11:58am
Interesting Press. SDMI information
The Howard Lake Ni Deposit is located on the northeast shore of Howard or Nickel Lake.
The deposit is hosted by a small wedge-shaped ultramafic sill enclosed by Glennie Domain migmatitic biotite gneiss. The sill has a length of at least 400 ft (121.9 m), is open at both ends, trends 025° and plunges 15 to 20° NNE. The sill has a width of 30 ft (9.1 m) and a depth of 80 ft (24.4 m) at the southern end increasing to a width of 50 ft (15.2 m) at surface and the sill narrows at depth. It extends to a depth of 24 m (78.7 ft) at the south end and 55.0 m (180.5 ft) at the northern end. The body consists of coarse-grained hornblende gabbro surrounding a core of medium- to coarse-grained, highly mineralized pyroxenite up to 30 ft (9.1 m) wide and 15 to 70 ft (4.6 to 21.3 m) deep.
The massive mineralization, which is preferentially concentrated in the core pyroxenites, consists of mainly chalcopyrite and pyrrhotite as disseminations and minute fracture fillings making up 1 to 10% by volume of the metagabbro and massive sulphide sheets or as lenses consisting of up to 80% combined sulphides in the metapyroxenite core. Sulphides consist of 60% pyrrhotite, 20% nickeliferous pyrrhotite and pentlandite, 10% pyrite and 10% chalcopyrite, giving ratios of Ni/Cu and Ni/Co of 2.35:1 and 23.27:1 respectively.
The mineralized zone has been traced over a length of 2500 ft (762 m); however, the main mineralization pinches out to the south and north.
Delineation drilling outlined a deposit some 560 m (1837.2 ft) long, 28 m (91.86 ft) deep and 6.7 (21.98 ft) wide. Delineation drill hole intersection assays ranged from 0.02 to 2.14% Ni, 0.04 to 0.59% Cu and up to 0.08% Zn for a blocked out deposit that was 585 ft (178.3 m) long, 20 ft (6.1 m) wide and 110 ft (33.5 m) deep. Averaged best assays gave 0.34% Cu and 1.03% Ni over 45 ft (13.7 m) and 0.5% Cu, 1.00% Ni over 27 ft (8.2 m).
Drilling of the main or A Zone inferred it to be 1800 ft (548.6 m) long by 22 ft (6.7 m) wide with an average depth of 93 ft (28.3 m).
By 1971, drilling of the "A" Zone had reduced the calculated zone dimensions to 1000 ft (304.8 m) long by 6 to 30 ft (1.8 to 9.1 m) wide and 70 ft (21.3 m) deep in the center and 15 to 30 ft (4.6 to 9.1 m) deep at the extremities.