Concentrate cars were specially designed to carry finely ground copper ore from a concentrator to a smelter.

This one was built by the Baldwin-Lima-Hamilton Company in December 1961 for the Southern Pacific Railroad, originally to haul concentrated copper ore from the Kennecott mine at Ray, Arizona, to a copper refining plant in El Paso, Texas. Its full-length bottom dump doors provided quick unloading at the destination.

This car was purchased by the Copper Basin Railway in 1993, where it hauled copper concentrate between Ray and Hayden, Arizona. It was donated to the museum by Copper Basin CEO Jake Jacobson in December 2015.

Currently, copper ore from the Ray mine is crushed to 3/4 inch, then further refined at a concentrator plant which grinds it to the size of sugar grains and mixes it with water and oil, allowing the copper particles to float to the surface as a froth. The resulting "concentrate" is skimmed off the top and shipped in cars like this to the smelter at Hayden, where it is refined into nearly pure copper.

This car was part of a 40 car order in class G-100-4 (gondola, 100 tons, 4th design of its class), capable of hauling 164,000 pounds of concentrate. It was more hopper car than gondola, with its high sides and unloading doors underneath actuated by air-driven cylinders. The interior of the car was only 21 feet in length, compared to 41 feet for the entire car. The unloading mechanism was in the space at each end along with the air brake actuators which could not be placed underneath the drop doors. The cars in this 1961 order P-3140 were numbered 341001 to 341040. In 1962 five more were built per order P-3159, numbered 341041 to 341045. They were all referred to as "341s" for short.

The Ray mine was a property of the Kennecott Copper Corporation until 1986 when it became part of the American Smelting and Refining Company (now ASARCO). The Copper Basin Railway, which serves the Ray mine, took over the Southern Pacific operation from Hayden to Magma Junction in 1986. These days it carries ore in hopper cars from the Ray mine to the Hayden crusher, and in concentrate cars from the Ray concentrator to the Hayden smelter. Smelted copper "anodes" used to be shipped by rail to Amarillo, Texas, but now move by truck.

When donated to the museum, the Copper Basin moved the car to Magma Junction where it was picked up by the Union Pacific and brought to the museum′s Tumbleweed Park location in 2015.

	Photo of the car being delivered in December 2015. The bottom of the car opens to allow copper concentrate to be dumped.
	End view of the car showing the shielded ends.
	View of the dumping mechanism.

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