The old Jacobs tungsten mill in Tucson

The Jacobs tungsten mill, located northwest of the intersection of Speedway and Silverbell, about 2 miles west of downtown Tucson, processed tungsten ore during World War 2. The ruins of the mill remain on-site.


Arthur Jacobs entered into a contract with the U.S. military to process tungsten which is a strategic metal used as an alloy to “harden” other metals, and to make armor and artillery shells.

The mill was operated under great secrecy, perhaps explaining why it was not listed in city directories at the time. Loads of processed ore were delivered under armed guard in government trucks to the Southern Pacific freight depot and shipped to Kansas City in special unmarked cars. Despite war rationing of gasoline, the mill and Arthur Jacobs Sr. were allotted an ample supply in order to run the mill.

The property is owned by the City of Tucson. In the mid-2000s, the City contemplated turning the property into “Painted Hills Natural Resources Park.” However, soil samples showed elevated levels of lead, arsenic, and cadmium. The City spent $200,000 for soil sampling, which one source says was bond money, while another source claims was a grant from the EPA.

A health consultation by the Arizona Department of Health concluded that these elevated heavy metals in the soil posed no danger to adults, but could prove dangerous to young children if they ate large quantities of dirt. They recommended that the site be remediated before use as a recreational park. The City has done no remediation on the site to date to my knowledge.

None of the reports says where the tungsten ore came from, but there are many tungsten deposits in southern Arizona. My guess is that the ore came from the Campo Bonito area in the Northern Santa Catalina Mountains and from the Little Dragoon Mountains (north of I-10, between Benson and Willcox. Another possibility is the Las Guijas mountains near Arivaca since there is reported tungsten production in the 1930s.

According to Wilson (1941): The principal tungsten minerals found in Arizona are the wolframites (ferberite, wolframite, and huebnerite); scheelite; powellite; cuprotungstite; and tungstite. Only the wolframites and scheelite have been of commercial importance. In Arizona, the principal source is tungsten-bearing quartz veins and shear zones in rocks that have been invaded by granite, granodiorite, pegmatite, or latite. A few placers, as in the Little Dragoon and Camp Wood areas, for example, have yielded notable amounts.

Lode and placer deposits from the Little Dragoons produced 55,000 pounds of concentrate during World War I and into the 1930s.

Mines in the Camp Benito area produced gold and tungsten intermittently since 1908. The gold may have contributed to the placers in Canada del Oro (see my article: The Gold of Cañada del Oro). Some of the claims were known to produce tungsten in 1941. Some production is reported in the late 1930s and early 1940s from mines near Mammoth, a few miles northeast of the Camp Benito area.

I have attempted to find out if Tucson still intends to clean up the area and create a park at the site, but I have been unsuccessful in reaching a knowledgeable City official.


Archaeological survey 2006:

This reference contains maps and many photographs of the mill ruins.

Health assessment The Arizona Department of Health and Agency for Toxic Substances and Disease Registry, U.S. Department of Health and Human Services in 2008:

Tungsten Deposits of Arizona

By Eldred D. Wilson, 1941

P.S. I asked the City about the status of the park project, here is their response:

Here are the responses to your questions that were forwarded our Environmental Services Department.

My questions:
1. Has the area in fact been cleaned up?
This area has not been abated. Impacted soils are still in place within the few areas on the site. City has installed fencing to prohibit public access and other preventive measures to contain soils from migrating off site.

2. If so where was the contaminated soil disposed?
No, soils are still in place as stated in response to Question 1.

3. Does the City still plan to establish a park there?
It is unknown at this time. The city hopes to abate this site as needed when funding is available. This property is owned by Parks and Recreation Department (P&R). Environmental Services does not know what P&R future plans are to develop this site as a natural park.

4. What is the status of the project?
Through an Environmental Protection Agency (EPA) Brownfields Cleanup grant the City of Tucson (City) completed an Analysis of Brownfields Cleanup Alternatives (ABCA), in December of 2008, which determined the most cost-effective and practical methods to remediate the site. In addition, in November of 2010 a Remedial Workplan was prepared and submitted to the Arizona Department of Environmental Quality (ADEQ) under the Voluntary Remediation Program. The selected remedial (cleanup) action alternative for this site recommended consolidation of the impacted soil within the limits of the former mill site footprint, and install an engineered soil-cover with clean soils. However, the cost of this remediation alternative is estimated to be $800,000, which far exceeded the City’s EPA Brownfields Cleanup grant of $200,000, and the City’s current budget capacity.

At this time, the Parks and Recreation Department does not have adequate funding to cover the associated costs for remediation of this site. The site is secured with a chain linked fence, which prohibits public access. Under ADEQ stormwater guidelines, the ADEQ – Southern Regional Office, Compliance Programs Unit approved the City’s Stormwater Pollution Prevention Plan (SWPPP), which outlines measures to prevent impacted soils from being transported via future stormwater runoff. In March 2014, the City completed the installation of preventive measures (Best Management Practices) as outlined in the SWPPP. The corrective measures will prevent impacted soils from leaving the site through the installation of waddles, and silt screens, and ensure these areas are contained onsite until funding for remediation is available.

You may contact Parks and Recreation directly if you would like more information regarding the future plans of this site.
David Barraza
City of Tucson
Environmental Services