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MOP smelter

This photo of the MOP smelter was published in "A Brief History of Butte," 1901.

In 1893, Butte’s mining operations were anything but consolidated. William Clark and Marcus Daly were certainly major players, but the Boston & Montana and Butte & Boston companies, controlled by the Lewisohn Brothers, were also independent, world-class establishments, together with many smaller players. Augustus Heinze started his career in Butte in 1889 as a 20-year-old mining engineer for the Boston & Montana Company.

Four years later, in 1893, Heinze and his brothers had incorporated the Montana Ore Purchasing (MOP) Company, to provide milling and smelting services to anyone who would pay. By 1894, the MOP smelter had opened on the south side of Meaderville. It was a huge, almost 500-foot-wide complex housing six massive reverberatory furnaces, 45 circular calcining furnaces, and two O’Hara furnaces each 100 feet long.

The reverberatory furnaces used the heat of coal combustion to reduce the metal to a molten state, but the fuel was not mixed with the ore as in a blast furnace. Calcining is a way of enhancing thermal decomposition of the ore short of melting. The state-of-the-art Allen-Brown-O’Hara furnaces were roasters that could process 60 tons a day when the MOP began operation. Six 80-foot chimneys served the reverberatory furnaces and two 150-foot brick chimneys vented the O’Hara furnaces.

A separate concentrator stood east of the smelter, across Meaderville’s Main Street. It took ore from trains and tramways for milling prior to passing it on to the smelter.

About three years after opening, the MOP smelter was pouring two million pounds of copper every month — not bad for an upstart. And the MOP employed about 700 men and returned stockholder dividends of 32%. Heinze had turned a $1.5-million investment into $25 million in amazingly fast time, and the company was no longer only handling the ore from others. Heinze, through his Montana Ore Purchasing Company and its subsidiaries, came to own the Rarus and other rich mines that became the centerpieces for litigation that dominated the late 1890s and early 1900s.

A serious fire in 1901 destroyed the O’Hara furnaces and much of the smelter complex, and another on August 28, 1902, consumed most of the concentrator. The concentrator was not rebuilt. Instead, ore was sent to Basin for concentrating, then returned to the MOP in Butte for smelting. Despite the fires, Montana Ore Purchasing had the third highest net earnings of a Butte company in 1902, at $600,000 to Amalgamated’s $1.29 million and its newly acquired division, Boston & Montana, at $1.64 million.

On February 13, 1906, the wars of the copper kings – at least the battles between Heinze and the Amalgamated (formed in 1899 and later renamed Anaconda) – were largely settled, and the MOP smelter and most of Heinze’s other assets were sold to Amalgamated, which closed the smelter in favor of their much larger operation in Anaconda. The MOP complex had been mostly removed before 1916, and the site today is within the Berkeley Pit. The smelter had stood just 600 feet east of the Berkeley underground mine shaft.

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Local geologist and historian Dick Gibson has lived in Butte since 2003 and has worked as a tour guide for various organizations and museums. He can be reached at


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