U.S. Department of the Interior, National Park Service
Applying National Register Criteria to Mining Resources
To be eligible for listing in the National Register of Historic Places, a mining property must be significant in American history, architecture, engineering, or culture and possess integrity of location, design, materials, workmanship, feeling, and association. In addition, the mining property must meet one or more of the four National Register criteria:
Under Criterion A (association with "events that have made a significant contribution to the broad patterns of history") a mining property may qualify for listing in the National Register through its connection with historic themes. Applicable areas of significance (listed in the National Register bulletin How to Complete the National Register Registration Form) include the following:
Under Criterion B (association with "persons significant in our past") a mining property will possess significance if directly related to a historically significant person. Examples would include properties linked to the following aspects of a person's historical significance: Herbert Hoover's mine engineering career before he entered politics, financier Bernard Baruch's rise to power through mine speculation dealings, General Sherman's early years as a California gold dealer, or bonanza king Horace Tabor's association with the Matchless mine in Leadville, Colorado. Applicable themes under Criterion B may include exploration/settlement, invention, law, literature, politics/government, and labor. (For additional information about Criterion B, see the National Register bulletin: Guidelines for Evaluating and Documenting Properties Associated with Significant Persons.)
Under Criterion C, a mining property possesses significance if it embodies "the distinctive characteristics of a type, period, or method of construction, or represents the work of a master, possesses high artistic values, or represents a significant and distinguishable entity whose components may lack individual distinction." Mining properties are often eligible for National Register listing within the following categories:
Under Criterion D, a mining property is significant if it contains information important in prehistory or history. Eligible resources which may provide such information include standing buildings or structures; surviving machinery; landforms such as mill tailings or mine waste rock dumps; or less visible physical remains such as privy pits, trash dumps, prospect pits, collapsed headframes, building foundations, roads, and machine pads or anchor piers. Application of Criterion D to mining properties requires the development of a good research design that not only identifies the research questions that are important to mining-related scholarship or science but also the information that is needed to answer the research questions. The information value of what remains can be evaluated within a systematic framework based on the following: developing research questions, identifying data requirements, and assessing the property's information content.
The research questions used under Criterion D should be important and derived from a scholarly field, or combination of scholarly fields, such as history of technology, historical archeology, archeology, anthropology, geography, architectural history, or landscape architecture. Among others, questions about variability and change in mining technology, mining society and culture, and mining landscapes should be considered. The conditions under which innovations in mining technology take place and are accepted or rejected (e.g., Basalla 1988), for example, or the impact of changes in mining technology upon the workplace (e.g., Dix 1988, Lankton 1991) are likely to be important. Similarly, questions about community formation (e.g., Hogan 1990), the miner's domestic household, the spatial organization of mining settlements, the production and consumption of commodities in the mining frontier marketplace, ethnicity and ethnic relations, gender, and social structure are likely to be important to scholarship on mining society and culture. And yet another group of questions that may be important to the application of Criterion D have to do with the characteristics and evolution of mining landscapes (Francaviglia 1992).
Identifying Data Requirements
"Critical information" assessment is the next step in Criterion D evaluation. The type of information needed to answer each of the questions identified in the research design must be stipulated. Questions about mining technology, for example, might require information about variability and change in architectural arrangements, the spatial arrangement of work-related activities, the arrangement and type of machinery, and landforms. Similarly, the information needed to answer questions about the mining frontier marketplace may include the consumer behavior of a miner's domestic household, retail and wholesale store inventories, transportation costs, and factory production.
Field Assessment of Information Content
The last step in evaluating the significance of a mine under Criterion D is field assessment. How does one know that a property contains critical information? First of all, it is necessary to make an inventory of what remains at the property that can provide information. The remains containing information may be buried or visible on the surface and may take the form of isolated artifacts, archeological features such as trash dumps or privy pits or wells, standing buildings and structures, machinery, or landforms such as mill tailings or mine waste rock dumps. Next, assess the quantity and quality of information contained in the remains at the property. Domestic trash dumps, for example, often contain artifacts carrying information about the consumer behavior of domestic households, household organization, gender, ethnicity, and social structure.
Ordinarily cemeteries, birthplaces, or graves of historical figures; properties owned by religious institutions or used for religious purposes; structures that have been moved from their original locations; reconstructed historic buildings; properties primarily commemorative in nature; and properties that have achieved significance within the past 50 years shall not be considered eligible for the National Register. However, such properties will qualify if they are integral parts of districts that meet the criteria or if they fall within the following categories:
Examples of historic mining properties that generally will not qualify for listing in the National Register include mining resources that are less than fifty years old, reconstructed mining towns that provide a contemporary portrayal of the frontier mining era, and collections of mining artifacts removed from their original locations and placed in museum collections. However, some of these properties may qualify for the National Register when they fall within categories A through G listed above. Examples include the following:
Moved Properties-Relocated properties generally do not qualify for the National Register. Under ordinary circumstances, this requirement places few constraints on the nomination of mining resources since they are not inherently moveable. However, certain components of mining properties are subject to relocation. For example, a shack used to store blasting powder may be small enough to have been moved from an inactive mining property to an active one. In addition, all manner of mining equipment is portable. Such equipment, classified as objects for National Register nomination purposes, would include ore carts, stamp mill batteries, drilling implements, tram cars, steam engines, water wheels, flotation tanks, and many other possibilities.
In general, if buildings, structures, or objects associated with mining activity are moved to other mining locations, these resources can be eligible as contributing features of a mining property provided that the most recent relocation occurred over fifty years ago. In addition, the moved resource must contribute to the significance of, and fall within the period of significance of, the mining property to which it was moved. If buildings, structures, and objects are more than fifty years old, but were moved less than fifty years ago, these resources will not contribute to the significance of the property. Although recently moved resources may not contribute to a property's significance, the mining property may still be eligible if it is predominately greater than fifty years old and retains integrity. Buildings, structures, and objects removed from their original locations and placed in museums for public display will not be eligible.
Resources Less than 50 Years Old-A historic mining resource achieving significance within the past 50 years can be listed in the National Register if it is exceptionally important. To qualify, a mining resource must be associated with important recent themes or developments (such as World War II) that scholarly or professional research has recognized as having a significant impact on the history of mining activity.
For example, certain less-than-50 year-old uranium mines may be eligible for the National Register. Congress created the Atomic Energy Commission (AEC) following the conclusion of World War II. Shortly afterwards, the AEC acted to stimulate uranium production by offering discovery and development bonuses. This practice fostered a uranium mining boom that continued until the bonus program experienced severe cutbacks in 1958. If sufficient scholarly documentation has been produced to demonstrate that particular uranium mines played exceptionally important roles in the development of the nation's nuclear capabilities, these mines may be eligible for listing in the National Register even though they are less than 50 years old. Establishing exceptional importance will require that such mines be compared with other uranium mines having similar associations and qualities in order to identify the strongest candidates for National Register listing.
Integrity is the ability of a property to convey its significance. To be listed in the National Register, a property must not only be shown to be significant under the criteria, but it also must have integrity. The National Register recognizes seven aspects or qualities that, in various combinations, define integrity. The seven aspects of integrity consist of the following: location, design, setting, materials, workmanship, feeling, and association. To retain historic integrity, a property will always possess several, and usually most, of the aspects.
When assessing the integrity of a mining property, it is important to remember that the National Register will accept significant and distinguishable entities whose components may lack individual distinction. As discussed elsewhere in this bulletin, the passage of time, exposure to a harsh environment, abandonment, vandalism, and neglect often combine to cause the deterioration of individual mining property components. For example, buildings may have collapsed, machinery may have been removed, and railroad tracks may have been salvaged. However, the property may still exhibit a labyrinth of paths, roads, shaft openings, trash heaps, and fragments of industrial activity like standing headframes and large tailings piles. Although these individual components may appear to lack distinction, the combined impact of these separate components may enable the property to convey the collective image of a historically significant mining operation. In essence, the whole of this property will be greater than the sum of its parts. In such cases, a mining property may be judged to have integrity as a system even though individual components of the system have deteriorated over time.
Because most historic mining properties will be abandoned and in poor repair, special care must be taken when evaluating integrity. The integrity of a mining property can not be judged in the same fashion as the integrity of a building. In some cases, buildings and objects related to mining will have been relocated and many original construction materials will be gone. The following sections explain how the seven aspects of integrity relate to historic mining properties.
Integrity of location means that a mine or mill remains in its original location. A place where mining once occurred is not inherently moveable, but components used to conduct mining or milling can be moved. Because machinery was often moved to several different mining properties during its lifespan, relocated historic mining equipment (i.e., equipment over fifty years old) can retain integrity under certain conditions. For example, 100-year-old mining equipment may have been moved to a newer mine that first went into operation seventy years ago. Although this equipment is not in its original location, it can contribute to the significance of the property since it has been in place for over fifty years.
In other cases, a mine may be historic (i.e., over fifty years old) and equipment at the mining location may be historic (i.e., over fifty years old), but the equipment may have been moved to the location less than fifty years ago. Historic equipment which has been at a mining property for less than fifty years will not contribute to a property's significance. However, this equipment will not necessarily detract from the property's integrity provided that the equipment generally serves to complement the setting.
Machinery moved explicitly for the purposes of display in a museum, park, or other interpretive site completely divorced from the place of historic mining activity has lost integrity of location. Machinery moved to "artifact gardens" also lacks integrity.
As mentioned earlier, mines and mills evolve through time with the introduction of new machinery or technology or the expansion of the mining operation. This evolution means that plants found in an unaltered state are rare. Thus, contemporary evaluation of a mill's integrity should not only be based on its conformance with an original construction plan, but also on its ability to illustrate the property's evolution through time. However, in cases where the property has undergone significant alterations during the past fifty years, the evolutionary process may result in a loss of integrity.
Mining operations were designed to follow established mine engineering practices that involved the flow of ore from the mine to the mill to the refinery. The engineering flow chart is essential in understanding the integrity of design. The lack of a minor feature in a system should not detract from its integrity, much in the same way that a missing cornice detail should not result in a loss of integrity for an entire house. However, the cumulative number of missing components must be taken into consideration.
When considering the cumulative loss of features, the evaluator must be sure to include buildings and machinery as well as the designed landscape, the moved earth, and piled stones or debris. For example, when evaluating a placer mine which has a historic hydraulic nozzle found in place but lacking any of the connecting system or evidence of canvas or metal pipes, take into consideration any earth works used to support the system. The pipe may be piled nearby to avoid being split by winter freeze or washed out by early spring flood. In this case, the hydraulic system may still have integrity of design because the machinery and earth works were found as they were meant to be in mid-winter. Underground works were designed as part of the mine system and, under some conditions, may receive consideration when establishing integrity of design. However, the underground works may be inaccessible and need not be inspected for National Register integrity if the mine is unsafe. The majority of underground mines are extremely unstable and should never be entered unless a State mining inspection has certified their safety. Thus, design integrity will generally be limited to the ability to reconstruct the flow chart from the mine opening and beyond.
Historic mines were industrial complexes that contained a multitude of functions. In many cases, the industrial features typical of a mining property are not pleasing to the eyes of contemporary viewers. For example, use of dredges may have left unsightly tailings piles that stretch for miles along stream beds. In other cases, a historic mining are may be littered with abandoned machinery and dilapidated buildings and structures. The appearance createdby these vestiges of bygone industrial activity represent important aspects of setting that can actually contribute to the integrity of a mining property.
Modern day instrusions can compromise the setting. Attempts to artificially embellish a mining property's setting can detract from the property's integrity. For example, the introduction of false-fronted boom-town structures can create an inappropriate setting that lacks historic authenticity. Other modern intrusions include recent mining activity activity that can compomise integrity of setting through the introduction of newer mass mining systems that destroy the historic mining property or leave it isolated. Also, recent settlement or development associated with gambling initiatives in a historic mining location can have a negative impact on integrity of setting.
Retaining integrity of materials requires evidence that sympathetic materials have been used during the course of previous repair or restoration of mining properties. Thus, a mine tramway with wooden supports should have been repaired with in-kind wooden materials. Because mine structures were often unpainted and expected to deteriorate, previous restoration efforts should have used untreated wood with the expectation that it would eventually need to be replaced too. However, inappropriate painting of mining properties will not automatically amount to a loss of integrity.
To the largest extent possible, mining properties should retain evidence of original workmanship. For example, the integrity of workmanship should be maintained in cases where an underground mine is open to the public. This would include preservation of such features as square-set timbering systems, the protection of pipe lines and track, and retaining the feel of the confined working space.
As abandoned industrial properties generally located in isolated areas, the sites of historic mining activity often evoke a strong sense of feeling when viewed by contemporary observers. Since mineral resources are non-renewable, mines close when ore reserves are depleted. Structures and equipment are simply abandoned. The image of abandonment has attracted more popular attention than active industrial operations. The feeling of a deserted historic mine can help reflect the character of the boom and bust cycles of mining regions. The loss of this feeling of isolation and abandonment due to encroaching modern development can diminish the integrity of a mining property.
Integrity of association will exist in cases where mine structures, machinery, and other visible features remain to convey a strong sense of connectedness between mining properties and a contemporary observer's ability to discern the historical activity which occurred at the location.
Three brief examples may help to summarize the process of applying integrity standards to mining properties. The first example involves those rare cases where a mining property consists of a complete mining system including shafts, transportation facilities, extant mill buildings, worker housing, and other aspects of the overall system. In such cases, the property would have integrity.
In the second, more typical, example, a mining property would lack visible buildings or contain only buildings that had been altered extensively. However, the property would have associated features like mine shafts, headframes, tramways, house and mill foundations, tailings piles, trash dumps, cemeteries, privies, and other isolated objects. Although buildings may be lacking or in a deteriorated state, this property would have integrity as long as key aspects of the mining system remain visible.
In a third case, visible buildings might remain extant, but the buildings may have been totally altered and the fundamental components of the mining system may have been destroyed by modern development. This property would have lost integrity.
The important principle inherent in each of these three examples is that the integrity of mining properties will frequently hinge not so much on the condition of the extent buildings, but rather on the degree to which the overall mining system remains intact and visible. This method of evaluating integrity requires a holistic outlook that comprehensively considers all the component parts of a mining system. If clear physical evidence of a complete system remains intact, deterioration of individual aspects of the system may not eliminate the overall integrity of the resource.
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