The 1920 Valley View Leasing and Mining Company Mill, commonly known as the Matterhorn Mill, is listed on the National Register of Historic Places under Criterion A in the area of industry at the local level of significance for its contribution to the 20th-century silver mining in Colorado's San Juan Mountains where it related directly to mining within San Bernardo Mountain. When constructed the Matterhorn Mill was a state-of-the-art flotation mill that utilized new technology to produce a higher grade concentrate than could be accomplished by the old-style stamp mill with concentration (shaker) tables.
Matterhorn Mill remains as nearly complete an example of a concentration mill using the first generation of the flotation system extant in the American West. Matterhorn Mill is further eligible under Criterion C in the area of engineering at the local level of significance. The mill is listed under the National Register Multiple Property Documentation Form The Mining Industry in Colorado: Mining Technology, Methods, and Equipment in Colorado: 1858-2005, representing the Ore-Concentration Facility—Concentration Mill property type.