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Shenandoah-Dives (Mayflower) Mill

Silverton, Colorado
County of San Juan.
2 miles northeast of Silverton on Highway 110 and 100 feet north of the highway.
National Register Number: 00000262
Resource type: Building.
Property type: Industry/Processing/Extract. - extractive facil.. The threat level was Watch in
Congressional District: CO-3 Certified Local Government: NO
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Current use/information: http://www.silvertoncolorado.com/index.asp?DocumentID=393.

Statement of Significance (as of designation - February 16, 2000):
The Shenandoah-Dives Mill is an intact and fully functional mill and includes all of its original equipment from the early 20th century. Constructed in 1929, the Shenandoah-Dives Mill is the finest extant example of a selective flotation mill. This property illustrates the transformation of the mining and milling industry and the distinctive characteristics of the hard-rock milling process during the first half of the twentieth century. Flotation, introduced to the American mining industry in 1912, was an innovative concentration process that separated valuable minerals from complex ores. This process efficiently and economically concentrated complex ores that were practically impossible to treat by earlier methods. The flotation process solved the problem of diminishing high-grade ore supplies and allowed increased minerals production.

This large mill is owned by a small nonprofit organization. Even the routine maintenance that is necessary to keep the structure in good condition is expensive and time-consuming, and is difficult for the group to manage. As a result, the roofs on custom ore bins have collapsed, allowing snowmelt to run through the foundation of the crushing plant. Every spring pieces of the roof need to be replaced. The historical society gives tours of the mill.

The historical society was awarded 3 grants to complete Historic American Engineering Survey documentation and a Historic Structure Assessment. The HAER documentation is almost completed and the HSA is scheduled to be completed in fall 2006. These documents identify needs and establish priorities. The historical society is now seeking funds to implement the much needed repair and maintenance plan.

Recommendation/Change since last report:
With the reliable assessments, funding agencies may be more willing to provide backing for certain top priority projects.

Comments and questions about the database may be directed to NHL_info@nps.gov