KNOB HILL MINE (GOLDEN PROMISE MINE)
Klondike Mountain, Republic, Republic District, Ferry County, Washington, USA

LOCALITY IMAGES


GEOLOGY
~50 Ma (million years ago) - The Golden Promise Au-Ag deposit formed along the hanging wall of the north- to northwest-striking Eureka fault in the Republic district. Graben formation between the subparallel Eureka and South Basin normal faults during a period of extensional faulting created a local basin that accumulated volcanic and fluvial/lacustrine deposits (Sanpoil Volcanics and Klondike Mountain Foundation). The period of graben formation and waning magmatism supplied the structural conduits and thermal energy for geothermal activity. Meteoric groundwater produced hydrothermal eruption breccias, vents and hot springs conduits that were responsible for Au-Ag mineralization (Fifarek et al., 1996).

MINERALS
*Electrum-
(Au, Ag)- Occurs as mm-scale grains typically associated with naumannite.
*Naumannite-
Ag2Se- Occurs as fine dark gray grains and as a major component of the ginguro bands (high-grade mm- to cm-scale dark gray layers found within the ore rock).

* photographed

 
ELECTRUM, NAUMANNITE,
QUARTZ (Var: Chalcedony)
 
Banded Au-Ag ore specimen
with
QUARTZ (Var: Chalcedony), NAUMANNITE


REFERENCES

Fifarek, Richard H., Devli, Barry D., and Tschauder, Jr. Richard J., 1996, Au-Ag mineralization at the Golden Promise Deposit, Republic District, Washington: Relation to graben development and hot spring processes, in Coyner, A.R., and Fahey P.L., eds., Geology and Ore Deposits of the American Cordillera: Geological Society of Nevada Symposium Proceesings, Reno/Sparks, Nevada, April 1995, p. 1063-1088.