The Royal Tharsis mine, one of the low-grade properties now being worked by the Mount Lyell M. & R. Co. Ltd., is situated on the western foothills of Mount Lyell, Tasmania. The ore-body is a lenticular mass of copper-bearing schist. Its horizontal dimensions are 500 ft. long by 70 ft. to 100 ft. wide, and it has been proved for a vertical depth of 1000 ft. from the surface to the level of the North Lyell tunnel. The country schists are cambro-ordovician metamorphosed volcanic tuffs, and lie against silurian conglomerate to the east. The ore-body is a short distance away from the contact and parallels the general north-westerly strike and 60 westerly dip of the country. There are no definite walls, the mineralisation fading out in the surrounding schist. The mine was originally worked more than 30 years ago, the ore-body being opened up at the surface by quarrying and explored by adit workings to a depth of 200 ft. The ore then won was used as metal-bearing flux in the pyritic smelting process, but the grade proved too low for profitable working. When this material was no longer required, the mine was abandoned until the completion of the North Lyell tunnel in 1928, when the facilities for working thereby afforded, and advances in metallurgical practice, warranted its again receiving attention.