The two main lodes, called Middleton's Lode and East Lode, trended north-south. Typical examples include gold lodes, as well as skarn mineralisation. Tin lodes were also found in outcroppings of cliffs. The mineralization zone consists of a series of copper-silver-gold bearing skarn lodes. The city was named for the leads or lodes of the deposits of valuable ores. The deposits were particularly rich, and included lodes of pure magnetic iron. Silver vein lodes were then the most productive until copper was discovered in 1888. Development work on gold quartz lodes was confined largely to the Turnagain Arm basin. Many gold occurrences are known, but no gold lodes are identified. It was established when silver lodes were discovered in 1864. In 1868, additional silver lodes were found near the settlement. Among these were those who would eventually discover the hard rock lodes on Cadwallader Creek. Progress was made in developing access to the Cosmo, Dolly and Watu lodes. The largest workable lodes are in Australia, Asia, and the United States. A new lock was constructed at Lodes End to provide an alternative route.