 By 1897, the Calumet & Hecla's Red Jacket shaft had reached a vertical depth of 4,900 feet, making it the deepest mine in the world.The neighboring Tamarack mine became the world's deepest mine for some years; it was bought by Calumet & Hecla, and became part of the Calumet & Hecla system.The Tamarack/C&H remained the world's deepest mine until about 1915, when its vertical depth of 5,500 feet was exceeded by the 5,824-foot depth of the Morro Velho gold mine in Brazil.