...copper is obtained from Lake Superior. Mr. Petherick, the well-known mining engineer, informed Dr. Percy that at Minnesota, in 18,54, not fewer than forty...single mass of native copper, weighing about 500 tons ! The native copper at Lake Superior in some places occurs curiously intermingled, but generally not...

...copper is obtained from Lake Superior. Mr. Petherick, the well-known mining engineer, informed Dr. Percy that at Minnesota, in 1854, not fewer than forty men...single mass of native copper, weighing about 500 tons ! The native copper at Lake Superior in some places occurs curiously intermingled, but generally not...

...Superior. Mr. Petherick, the well-known mining engineer, informed Dr. Percy that at Minnesota, in 1834, not fewer than forty men were engaged during twelve...single mass of native copper, weighing about 500 tons! The native copper at Lake Superior in some places occurs curiously intermingled, but generally not...

...Petherick (the well-known mining engineer), that in 1854 not fewer than forty men were engaged at Minnesota during twelve months in cutting up a single mass of native copper weighing about 500 tons. (Percy's " Metallurgy," vol. ip 309.) The value of copper has since then fallen one quarter, and it...

...Percy, in his large work on Metallurgy, states, on the authority of a wellknown fining engineer, ' that at Minnesota, in 1854, not fewer than forty men...single mass of native copper, weighing about 500 tons !' Copper ores are found in a great many countries, but it is only in some that they are smelted. Large...

...copper aggregates in the vein deposits are very large. Percy mentions that in 1854 not fewer than 40 men were engaged during twelve months in cutting up...weighing about 500 tons. Native copper is generally remarkable for its toughness. A specimen from Chile about f in. in thickness is instanced by him as...