Cargill Township carbonatite complex, District of ... - Geology Ontario

CARBONATITE - ALKALIC ROCK COMPLEXES: CARGILL TOWNSHIP
residual apatite concentrations of economic value within a karst-like topography
developed on the surface of a carbonatite intrusion (Sandvik and Erdosh 1977,
p.94). The company completed 183 holes using reverse circulation techniques
and outlined a residual phosphate-bearing deposit of 56.7 million tonnes (62.5
million tons) with an average grade of 19.696 PaOs (Sandvik and Erdosh 1977,
p.96). In evaluating the complex the company completed 18 480 m (60,626 feet)
of dominantly reverse circulation drilling (private files, International Minerals and
Chemical Corporation). Included in the above is approximately 1200 m (4000
feet) of diamond drilling which was completed to sample bedrock geology. Addi
tional tonnage of phosphate-bearing material may exist below the present calcu
lated pit bottom (152 m or 500 feet) and along the northeast extension (Sandvik
and Erdosh 1977, p.96). Dolomitic and sideritic carbonatite form the protore for
the residuum deposits (Sandvik and Erdosh 1977, p.96). Fresh calcitic car
bonatite generally contains less than 596 P2O5 (Sandvik and Erdosh 1977, p.96).
Overlying the residuum deposit is a crandallite-rich layer that contains rare
earths. It has not been evaluated as to its economic potential (Sandvik and Er
dosh 1977, p.90). Vermiculite, niobium, quartz sand, and clay may be present in
commercial quantities (Sandvik and Erdosh 1977, p.90). Sandvik and Erdosh
(1977, p.90) reported that uranium is not present in the deposit.
The author collected two specimens of sulphide-rich drill core from the core
of International Minerals and Chemical Corporation and submitted them for as
say. The results are as follows:
Hole Depth Percent Copper Percent Nickel
55 74.0-74.5 0.37 0.15
30 179.3-179.7 0.18 0.02
The samples were also tested for platinum group metals but these, if present,
occur in quantities below the limits of detection. The assays were completed by
the Geoscience Laboratories, Ontario Geological Survey.
To simplify their work on the complex, International Minerals and Chemical
Corporation subdivided the complex into north and south subcomplexes, and a
west subcomplex located 4 km west of the south complex (Sandvik and Erdosh
1977). Up to the present, work has been concentrated on the south subcomplex
with more limited drilling on the north subcomplex.
SHERRITT GORDON MINES LIMITED
In 1979 Sherritt Gordon Mines Limited obtained an option from International
Minerals and Chemical Corporation (Canada) Limited and commenced further
evaluation of the apatite residuum at Cargill. The company completed sonic drill
holes for a total length of 4878.0 m (16,000 feet). The SG and P series of holes
were completed in 1980 to 1981.
The company cleared and stripped the deposit and obtained a bulk sample
for metallurgical testing. Pilot plant tests conducted in 1981 confirmed previous
recovery assumptions. Laboratory and pilot plant scale acidulation tests were to
be conducted in 1982.
Kilborn Limited (1981) prepared a report presenting a number of grade and
tonnage calculations for the Cargill phosphate residuum. These data were calcu
lated to extract varying tonnages from the core of the deposit.
Recovery tests for phosphate were completed in 1982 (Wyslouzil and Wil
liamson 1982).
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