This section is intended to be a brief review of the study area. For details of the image processing, ground studies, and spectral databases, please contact Spectral International for additional documentation.

Brief Description Of Site

The Dragon Pit is located in northeast Juab County, Utah, in the Main Tintic base and precious metals district. The Tintic mining district is part of the EPA Utah AML hyperspectral evaluation study, with both government and commercial vendor contributors.

The Dragon Mine was the second mine discovered in the Main Tintic District (Morris, 1985). It is believed to be one of the largest halloysite mines in the world (Hall, 1985) outside of New Zealand. The Dragon Mine is a well-known open pit and underground locality for the clay mineral halloysite, which is a Kaolin Group mineral. In the mid-1940's, after extensive research by the Filtrol Corporation, it was determined that Dragon halloysite was more efficient than activated montmorillonite as a filter catalyst in petroleum cracking operations. The process was patented and mining of the halloysite began in 1949 and continued until 1976, with 1,350,000 tons valued at around $50,000,000 extracted. A synthetic catalyst replaced the halloysite and the mine was deactivated in the late 1970's.

The Dragon also contains large masses of previously mined iron oxide bodies. Presently, the Dragon Mine is inactive, but is partially surrounded by large dumps and waste piles of limonitic iron-bearing materials, which superficially suggest the presence of an acid-drainage problem.

Why Site Was Chosen

For this part of the NASA EOCAP Project Phase I study, the Dragon halloysite mine, in the Main Tintic Mining District, Utah was chosen. This site hosts a large variety of minerals and poses some unique challenges to the discrimination of very similar mineral species using hyperspectral remote sensing techniques. The Dragon Mine was chosen by consensus among the commercial participants of the EPA Utah AML project as a common, ground-reference site where field calibration data and airborne images could be compared.

In July of 1999, the EPA AML group participants visited the Dragon Pit for a day. The objective was to demonstrate the field instruments used for ground truthing, to collect samples, and to generally familiarize the participants with the geology and terrain of the site. Spectral International and its NASA EOCAP collaborators were pleased to participate as field trip guides, to provide in-situ field instruments, and to collect a representative suite of samples for spectral analysis.

Geologically, this is a low sulfur environment. There is very minor jarosite and supergene gypsum, the latter most likely deposited through ground water action on the carbonate. The disseminated pyrite does provide a source for mild acidic ambient temperature solutions. The vivid yellow of the dumps primarily is a function of iron oxides and not sulfates. This is a source for considerable discussion in the reports on the images.

The foregoing points illustrate a very important consideration in the evaluation of such sites as the Dragon for acid mine drainage potential. The Dragon in fact is fairly benign. However, visually the site is deceptive, as it appears jarositic. It is also associated with a known lead-zinc-silver district, and this fact again may be misleading in terms of potential heavy-metal hazards. There are reports of small base metal veins at the Dragon (Kildale and Thomas, 1957). However, these are not large enough to be exploited, nor to contribute significant amounts of toxic metals to the environment. The other important consideration is the climate. This is a semi-arid zone with minimal precipitation, and therefore lacks the ground and surface water volumes required to concentrate and move metals any distance.

The combination of common interest among the EPA project participants and the need to identify whether there were any potential hazards associated with the Dragon Pit were the primary motivations in choosing this site. Ultimately, this site study will advance the general use of hyperspectral data and techniques for evaluation of transitional minerals. The site also provided a common comparison site for other sensors being used in the EPA Utah AML project (AVIRIS high- and low-altitude data and Probe I), which otherwise could have been difficult to arrange in common at our other Phase I sites.

These images show the excellent correlation between ground and image data. Note that alunite ground samples (lower image) match red pixels in the upper image.

SUMMARY OF STUDY AREAS (INCLUDING SPECTRAL ANALYSIS)

The Dragon Mine study was initiated as a ground truthing calibration reference site for the AML Utah EPA project. Because of the mineral diversity, economic, and environmental applications and compactness of the site, it has become a benchmark case study for hyperspectral remote sensing instrument and algorithm evaluation.

The SFSI data for the Dragon Pit and surroundings have proven to be of high enough spectral and spatial quality to allow discrimination of very similar (crystal structure and chemical formula) mineral species, specifically halloysite and kaolinite. This cannot be done reliably with high-altitude AVIRIS due to both the broader bandwidth of the detector and the lower spatial resolution, which limit the discrimination of such mineral series to only the pure endmembers and to relatively large exposures of the minerals.

This image shows a progression resulting in zoning from halloysite (purple) to kaolinite (dark blue) through magenta, red, yellow, black (equal amounts of both minerals), light green, dark green, cyan and dark blue. This is an astounding image. It shows octahedral layer zoning within the minerals and tracks weathering and distributed waste from the mining. Note the concentrations of kaolinite (yellow arrows) on the north dumps. These are waste products in dump truck load piles from the pit or underground.

From published preliminary results from processing of the Probe I hyperspectral sensor data, the spectral processing performed on the SFSI data seems better able to correctly identify jarosite, kaolinite, and halloysite distributions and relative concentrations. This could also be a function of processing algorithms. Nontronite, an important iron smectite mineral for understanding the hydrothermal processes forming the Dragon deposit and for evaluating environmental characteristics of the wastes and exposed rocks, was identified from SFSI data and not included in the available Probe I processing.

The Dragon Mine initially was represented as a potential acid drainage site with toxic metals. Field and hyperspectral work have shown that the Dragon Pit wastes and in-place rocks, and nearby mine wastes, are environmentally innocuous due to the apparent low content of pyrite and other sulfides. The low sulfide content is a function of the type of mineralizing system, which was confirmed by the species and abundance of the infrared-active minerals identified during this project.

This overlay of sample locations on an orthophoto of the Dragon Mine shows the distribution of jarosite at the Dragon Mine. Although jarosite is present, it is only present in small amounts. While jarosite can be identified with field-work on a hand sample level, it would be difficult to identify in significant amounts from the air without over-processing the image spectral data and including iron oxide minerals in the processing.

WATERSHED ASPECTS OF RESULTS

The Dragon Pit and surroundings do not appear to pose any chemical hazard to the Dragon Canyon or greater Tintic Valley watershed. There may be an intermittent issue of sedimentation from the Dragon mine dumps, but this site is not the only contributor of sediment. Sedimentation also is expected to be much higher in 2000 and subsequent years in this area of the larger watershed due to an extensive brush and forest fire (of 1999) on the west side of the East Tintic Mountains, including this tributary watershed.

COMMERCIAL IMPLICATIONS AND MARKET STRATEGY

The Dragon Pit area provides an example of assessing potential environmental impacts from what at first glance appears to be a potentially hazardous site. Ground spectral and hyperspectral surveys of such a site are very important for proving or disproving this potentially costly hypothesis. Commercially, the ability to identify environmentally benign sites is as important to PRPs (potentially responsible parties) and to the various regulatory agencies as knowing where the greatest hazards are that need remedial action.

The ability to test the SFSI/CASI combination against other sensors, AVIRIS and Probe I, at a common and well characterized site such as the Dragon Pit provides the ability to really identify the relative advantages and limitations of different sensors and the information extraction and verification methodologies. This clearly ties into commercialization and market strategy as part of knowing the competition and in identifying technical areas for hyperspectral techniques and accuracy assessments that need to be addressed before going fully operational in the commercial world.

APPLICATION OF STUDY AREAS TO POTENTIAL COMMERCIALIZATION AND MARKETS

The Dragon open pit clay mine in the Tintic District is fairly innocuous chemically, and so on its own is a low priority for reclamation other than for removal of physical hazards. Nonetheless, this mine was chosen as a case study because it serves as a common analysis and reference site for testing multiple hyperspectral sensors and processing techniques within the context of the EPA Utah AML project.

The clay mine also served as an excellent test of hyperspectral technology for discerning fine differences among clay minerals, in this case halloysite and kaolinite. This by itself may seem academically of interest. However, this finding has potential for environmental markets by proving the technology's ability to discern important, fine mineralogical and chemical differences among mine and mill wastes, as well as other wastes, that can affect their prioritization for further investigation and remediation.

Some clays have great ability to adsorb or absorb metals and other contaminants, and subsequently release them to the environment when chemical conditions change. Ability to identify differences among clays, therefore, is an important aspect of proof of the technology and for making inroads to the environmental industry for further commercialization and marketing.

COMMERCIAL IMPLICATIONS OF RESULTS

The Dragon Pit area provides an example of assessing potential environmental impacts from what at first glance appears to be a potentially hazardous site. As shown in the case study (Volume V), the in-place and waste materials are strongly, eye-catchingly colored, conditions that would lead a casual observer to believe that something in the materials must be of environmental interest.

The initial assumption could be that the strongly yellow materials are jarosite, thereby indicating acid-production potential, and that the bright red iron oxides are related to oxidized sulfides. Ground spectral and hyperspectral surveys of such a site are very important for proving or disproving this potentially costly hypothesis. Commercially, the ability to identify innocuous sites is as important to potentially responsible parties (PRPs in EPA parlance) and regulatory agencies as knowing where the greatest hazards are that need remedial action.

The ability to discriminate fine differences among the clays and map distributions at this mine serves as a commercializeable example for both environmental and clay mining markets. The ability to test the SFSI/CASI combination against other sensors, AVIRIS and Probe I, at a common and well characterized site provides the ability to really identify the relative advantages and limitations of different sensors without the distraction of differing site conditions from study area to study area as has been common in available past comparisons. This clearly ties into commercialization and market strategy as part of knowing the competition and in identifying technical areas for hyperspectral sensors and techniques that need to be addressed before going fully operational in the commercial world.