The area of the General - Grant is underlain by the Mississippian to Lower Permian Milford Group. Upper Triassic to Middle Jurassic intrusions cut the strata. Grey-copper (tetrahedrite) carrying small amounts of galena and sphalerite and high amounts of silver within small shoots in quartz-filled fissure veins which cut siliceous limestone near a granite contact. The vein has been accessed by two tunnels with considerable development. A sample across a 20-centimetre pay-streak in one stope gave: 0.69 gram per tonne gold, 21,579 grams per tonne silver, 13.3 per cent lead and 4.8 per cent zinc (Annual Report 1921). A shipment of 5 tonnes in 1972 yielded 7589 grams of silver, 107 kilograms of lead and 146 kilograms of zinc. In 1889 and from 1916 to 1921, 22 tonnes of ore was shipped and 298,718 grams of silver and 2489 kilograms of lead were recovered.