A LOOK AT LINDSLEY

the South Range of the Sudbury Igneous Complex The deposit comprises four zones of mineralization, termed Zones 1 to 4 Falconbridge purchased the lot holding the deposit in 1937 and drilled off the downward extension of Inco’s Blezard deposit during the period 1941 to 1957 In 1970, this zone (Zone 1) was renamed the Lindsley deposit in honor of Thayer Lindsley, founder and first president of Falconbridge In 1971, operators couldn’t afford to continue shaft-sinking, which was stopped at only 93 m

Drilling on the property during 1969 to 1974 led to the discovery of Zone 2, 90 m west of Zone 1 Drilling of hole B-51, which was started in 1986, intersected Zone 2 In 1987, hole B-51 was deepened and intersected Zones 3 and 4 Zone 4 is the platinum group metal- , gold- and copper-rich sulphide entirely within footwall granite at a depth of greater than 1,200 m below surface Zone 3 occurs in the sublayer below Zone 4 This discovery was termed Zone 4 In 1987, deepening of hole B-51 resulted in the discovery of Zone 3, which, occurs in the sublayer below Zone 4

Regionally, the Lindsley deposit lies within the Sudbury Igneous Complex, which is situated at the junction of the Superior, Southern and Grenville Provinces of the Canadian Shield The Sudbury Igneous Complex is approximately 18 km in strike length and 24 km wide and hosts nickel-copper deposits which are divisible into four main groups: typical South Range deposits, typical North Range deposits, off-set dyke deposits, and fault-related deposits The Lindsley deposit has many features typical of the South Range ore deposits, which often occur in depressions within the footwall of the Sudbury Igneous Complex and are referred to as contact or sublayer-type deposits

Rocks at the Lindsley deposit strike northeast and dip 45 degrees to the north above the 900-m elevation With increasing depth below 900 m, the dip increases to vertical; and between 1,050 and 1,200 m, the dip rolls over to the south to approximately 45 degrees , forming a “nose-like” structure

From south to north, the stratigraphic sequence is granite, basalt, sublayer, and amphibole-quartz-rich norite The granite and basalt form the footwall and the norite forms the hangingwall of the orebody above the 900-m elevation Below this depth, the hangingwall and footwall are reversed The sublayer hosts Zones 1, 2 and 3, whereas Zone 4 is entirely within the nose-like structure, which itself is within the footwall granite Zones 1 and 2 are on the footwall side of the sublayer 660 m and 1,020 m below surface respectively, where the basalt-sublayer contact is altered to amphibolite-grade facies of metamorphism Zone 3 occurs about 1,440 m below surface where the sublayer is overturned and the dip is reversed Consequently, Zone 3 occurs on the hangingwall side of the sublayer Zone 4 is centred at about 1,290 m below surface

The sublayer, which occurs between the basalt and the norite, hosts contact breccia ore of the Sudbury Igneous Complex It contains basalt and silica-rich fragments within a very fine-grained norite matrix In Zones 1 and 2, from hanging wall to footwall, mineralization in the sublayer consists of four types; interstitial sulphides, ragged disseminated sulphides, inclusion-bearing sulphides, and massive sulphides In Zone 3, these four types of mineralization occur in order from footwall to hangingwall

Mineralization is also found in Zone 4 within the footwall granite nose-like structure Here it is similar to the massive sulphide found in the sublayer, but it is enriched in copper, gold, platinum and palladium and is on average, three times the grade of all other Falconbridge mines in the Sudbury area The average grade of Falconbridge’s other mines is 1 53% nickel

Falconbridge is to begin sinking the T-L exploration shaft to 1,633 m in early 1989 Exploration headings driven on the 1,290- and 1,560-m level s will facilitate the underground exploration of Zones 3 and 4 with underground drilling and drifting planned for 1991 A feasibility study will be completed by 1991 or early 1992 Pamela Phillips is a geologist and project co-ordinator for Greenstone Resources in Toronto She would like to thank Falconbridge for its assistance (in particular, Chief Project Geologist David Comba)

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