The Dragon Mine is a kaolinite-halloysite industrial clay deposit located in the historic Main Tintic base metals District in north central Utah. It has been targeted as a potential acid mine drainage site. It is also a good metals exploration case study.

The Dragon Mine was discovered in 1870; initially mined, unsuccessfully, for Au-Ag-Cu-Pb; then for smelter flux iron oxide ores (seen in the picture below); and from 1949-1976, halloysite was extracted for use as a petroleum cracking catalyst.

The Dragon is a Halloysite Clay and iron oxide replacement body developed along the Sunbeam-Dragon Fissure Zone, a 150m wide, N-NE trending structure, which lies on the contact between the Silver City Monzonite and the Ajax Dolomite.

Alteration minerals include halloysite, kaolinite, alunite, illite, montmorillonite, nontronite; calcite and dolomite, with minor jarosite, pyrite, gypsum, and gibbsite. 

The Dragon deposit was emplaced before Tintic District sulfide mineralization and contains few sulfides. Minimal sulfur and potassium sources are available for acid generation. Dragon was formed by Contact Metasomatism along the Dragon Fissure where the dolomite host was hydrothermally replaced with low temperature clays. Massive iron oxides and nontronite occur along the carbonate intrusive contact. Clays in the Dragon Fissure Zone are in the grey diagonal across the pit face in the photograph below.

There is no acid drainage problem at the Dragon. The iron is limonite from oxides, not jarosite (sulfate), which is an acid indicator. Jarosite occurs only locally and is a product of minor disseminated pyrite from post-Dragon emplacement. Toxic metals are rare. The semi-arid climate does not provide sufficient ground water to move metals or toxic materials into the drainages.

This 20m pixel AVIRIS RGB image shows the entire Tintic District. The pale blue areas highlight alteration at the mines and other clay bearing areas. Vegetation is green and red, indicating grasslands, fields and slopes. The district extends from Eureka (E) south. The Dragon (D) is in the south central part and is on a N-NE trend into East Tintic. Note the blue speckles of dumps around the Dragon. This image was processed by Alistair Lamb, UK.

These images show the diversity and great detail from the SFSI-2 Hyperspectral Airborne Sensor data, collected over the Dragon Mine, with 4 meter ground pixel resolution, on 5 nm band centers. The image above maps the distribution of kaolinite and halloysite. The colors represent the mineral mixtures from purple (halloysite only)-> magenta-> red -> yellow -> black (1:1) -> green -> sea green ->cyan-> to blue (kaolinite only). This image has been verified with PIMA™ ground data.

To understand the small (4 meter) detail detectable with the SFSI-2, compare the structures in the pit face in the cross-section cartoon to the alunite image. The hydrothermally derived alunite follows the structures and fills them where they are exposed on the Pit High Wall face. Red is best fit.

The spectra are extracted from the images and represent mineral end members found in the SFSI data. The order is (top to bottom): alunite, kaolinite, halloysite, illite, smectite, nontronite and calcite. These images processed by William Peppin - Advanced Software Applications, Reno, NV.