‘AN’ WASTE SERPENTINE [J ARGILLITE ALTERATION ZONE CASSIAR ASBESTOS CORPORATION LIMITED ca! wine casi ye So UMBI SECTION 23,400 N T[arenoves (] FAULT ZONE = ADIT 8 DIAMOND DRILL HOLE FIGURE 5— Cross section: 23,400 N. voleanic flows are encountered, until, in the “south peak” area of the mine, the wall rock is predominently volcanic. These rocks are generally structureless, with the general flow direction sub-parallel to the ser- pentine emplacement. A major fault system (striking east-west and essentially vertical), sub-parallel to the west fault and 70° shear, occurs in the southern portion of the pit. This system, known as the south fault, can be considered as an important area of future exploration due to its apparent southern termination of the ore and its genetic relationship with other major systems. Geological mapping of all fresh faces is conducted throughout the pit to provide the geological base for pit planning and slope analysis. Mine Development SURFACE DIAMOND DRILLING An annual program of HQ diamond drilling was in- itiated in 1971 within the Cassiar pit to provide the on-going grade and fibre characteristics needed for mine planning, and to explore the fibre zone currently beneath the open-pit design limits. Preliminary dia- mond drilling was attempted on the main orebody in 1951, but was largely unsuccessful due to poor core recovery. Diamond drilling was also carried out in 1961 and 1963 in the cirque to the north of the orebody to determine if any fibre-bearing structures followed the serpentine band. Pit waste dumps are now located in this area. Total footage drilled to date is nearly 39,000 ft (11,887 m) (Fig. 5). Diamond drilling at Cassiar presents problems. Some are unique to serpentine, whereas many are common to the mining industry. Drilling within the orebody is attempted on 100-ft (30.5-m) grid centres where pos- sible. The nature of the serpentine host rock, chrysotile fibre veinlets and shear zones make core recovery dif- ficult. However, much success has been achieved since the initial 1951 drilling using HQ wireline equipment, with reduction to NQ where necessary. Deviation of planned hole direction in the serpentine is minimal. Drilling from the hanging-wall argillites into the serpentine presents other problems. Due to the domi- nant hanging-wall bedding, all drill holes deviate to the north. This has resulted in holes being laid out to compensate for the expected deviation, which naturally precludes vertical holes. Down-the-hole methods in the argillites will be investigated in 1978 to obtain a ver- tical hole, with coring starting at the serpentine. Drill- ing in 1978 and subsequent years will be carried out in the pit to obtain further information for future mining and from the peak to determine the extent of the fibre zone at its southern end (Fig. 6). By the fall of 1980, a final decision must be made on the final design, which will influence both this and succeeding designs. Each design has a maximum waste yardage to be weighed against former ore. However, if by drilling, the ore is shown to be appreciably reduced (automatically increasing waste yardage), then the 10