Qeensland Geological Record 2007/02

A summary of field inspection of mineral deposits of the Hodgkinson Province

JSF Lam & PD Garrad

The Hodgkinson Province hosts several operating mines producing significant tonnages of base metals and tin in Queensland. Other advanced mining project developments are for base metals, tungsten and gold. Exploration for nickel and diatomaceous earth has met with some success. Minor limestone is being mined from a small quarry.

The Collingwood lode tin deposit situated 30km south of Cooktown is a type of siliceous-sheeted greisen lode associated with pegmatite. It is the largest underground tin mine in Australia producing ore grade at 1.3% cassiterite with grains up to 2-3mm size. Reserve estimates as of 30 June 2006 total 953 900t at 1.19% Sn.

The Kangaroo Creek deposit is currently the only surface operating alluvial tin mine in Queensland. Alluvial tin is obtained from 0.5m thick cement beds of rounded quartz pebbles, containing very fine-grained cassiterite underneath sandy alluvium up to 2m thick. Inferred resource should extend the one man operation for the next ten years.

The Watershed Grid is a world class deposit of scheelite (calcium tungstate), situated 150km north-west of Cairns. The project is at the pre-feasibility stage; with a program of in-fill drilling, bulk sampling and metallurgical development in progress. The Watershed deposit has an Inferred Resource of 21.79Mt at 0.26% WO3 for a contained WO3 content of 56 300t.

The regional north-north-west trending Retina shear hosts a number of shear-related antimony and gold deposits associated with mylonite zone in metasediments. These deposits are being explored by Republic Gold Ltd. Exploration has outlined resources of 2 847 000t at 1.7g/t Au containing 156 000ozs of gold within the Sleeping Giant deposit. The Northcote deposit contains 9 420 000t at 1.7g/t Au containing 573 000ozs of gold.

Solomons Mine Pty Ltd has produced small tonnages of copper sulphate (pentahydrate) crystals from copper ore by the open cut method at the Tartana West deposit.

Kagara Zinc Ltd has several advanced exploration targets and opencut and underground mines in the Hodgkinson Province. The King Vol and Monte Video prospects situated on the western margin of the Hodgkinson Province occur within sediments of the Chillagoe Formation. Oxidised zinc and lead mineralisation is associated with surface ferruginous gossan karst collapsed breccia overlying massive sulphides skarn deposit. Diamond hole drilling at King Vol showed that the mineralised oxide zones were derived from primary sulphide mineralisation.
Mining is conducted at the Mungana deposit which has been classified as a low sulphidation porphyry Cu-Au skarn deposit developed within carbonate and aluminosilicate host rocks, which contains a resource of 1.96Mt at 14.4% Zn, 2.8% Cu, 2.2% Pb, 187g/t Ag and 1.14g/t Au.

The Balcooma deposit consists of four separate stratigraphic horizons containing copper-rich massive base metals sulphide mineralisation with three recorded types of mineralisation as magnetite, pyrite-chalcopyrite and sphalerite-galena-pyrite. Balcooma will be mined as an underground operation and a decline is currently being developed.

Exploration has advanced the progress of the Bell Creek lateritised nickel enrichment (>1% Ni) deposit, and the Glen Eagle and Conjuboy diatomite deposits.

Field inspection of several minor gold and rutile occurrences has not identified suitable hand size specimens for mineral alteration study or age dating. Diatomite samples were collected from selected occurrences.

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