Mining Intelligence and News
United States

Kettle River-Buckhorn Mine

Click for more information



Mine TypeUnderground
StatusClosing / Closed
  • Gold
Mining Method
  • Cut & Fill
  • Longhole stoping
Production Start... Lock
Mine Life... Lock
SnapshotKettle River-Buckhorn mine ceased production in 2017.

Crown Resources Corporation is the holder of a waste discharge permit in respect of the Buckhorn Mine, which authorizes and regulates mine-related discharges from the mine and its water treatment plant.

The Company was issued two Notices of Violations in 2021 from the Washington Department of Ecology (WDOE) asserting that the Company had failed to meet its obligations under the renewed Permit. Consolidated lawsuits by the Okanogan Highlands Alliance (OHA) and the Attorney General for the State of Washington against Crown Resources and Kinross under the Clean Water Act and relating to the renewed permit were stayed in April 2023 to enable the parties to pursue settlement through court-ordered mediation. In March 2024, OHA and the Attorney General terminated settlement discussions.


Kinross Gold Corp. 100 % Indirect
Echo Bay Minerals Co. (operator) 100 % Direct
The Kettle River-Buckhorn mine is owned and operated by Kinross’ wholly-owned subsidiary Echo Bay Minerals Company.

Deposit type

  • Skarn


The Buckhorn Mt. gold deposit ranks among the largest "gold skarns" in North America.

Gold mineralization is associated with a variety of skarn mineral assemblages, and is concentrated in a variety of stratigraphic/structural settings. The extent of "economic" (i.e.>0.042opt Au) mineralization is described as having dimensions of about 3,000ft x 1,000ft x 800ft. Sulfide mineralization, principally pyrrhotite, is more extensive. Within the broad zone of gold mineralization, no economic concentrations of other metals have been identified. The overall Au:Ag ratio in the Buckhorn Mountain gold deposit is about 2:1.

Several discrete mineralized zones comprise the Buckhorn Mountain gold deposit. On the basis of location, geometry, associated skarn mineralogy, and perceived protolith; BMG defined four "ore" types. In order of importance with respect to the gold mineral resource, these "ore" types are:
* Southwest Zone,
* Gold Bowl Garnet,Gold Bowl Magnetite, and
* Andesite.

Gold mineralization constituting the Buckhorn Mountain gold deposit occurs within a broad zone of pyrrhotite mineralization. Macroscopically, gold in all ore types is spatially associated with occurrences of bismuth minerals and of arsenopyrite. Bismuth minerals are reported to be more abundant in the GB than in the SWZ, although gold grades are on average much higher in the SWZ. Visible gold had been considered rare overall. However, visible gold was logged in over 50% of samples which assayed >1.0opt (n=40) from the Crown 2002 SWZ in-fill drilling.

Microscopically, there is a very strong association between gold and bismuth minerals, which include native bismuth, bismuthinite (Bi2S3), and joseite (Bi4TeS2/Bi4Te2S) (Schurer and Fuchs, 1990 and 1992). Gold grains have been observed most commonly attached to and within these minerals, and this association has been observed in all ore types. Another common but subordinate mode of occurrence for gold is within or attached to certain skarn gangue minerals, notably pyroxene, epidote, and amphibole. Gold has also been observed, not uncommonly, encapsulated by bismuth minerals or skarn gangue.

Gold in all ore types occurs as generally <20 micron and often <10 micron grains of native metal. Limited microprobe analysis indicates an `average' silver content of 9-14%, and up to 0.5% bismuth.

Mineralization in the Southwest Zone.
The SWZ "ore-type" is synonymous with the stratabound, marble-associated, gold-mineralized skarn in the southern portion of the property where the stratigraphic sequence is well defined and relatively continuous. Skarn mineralogy is variable and crudely zoned with magnetite and garnet more abundant towards the east (proximal to the pluton) while pyroxene dominates the western (distal) portion. Sulfide mineralization is dominated by pyrrhotite, which averages 3-5%, and ubiquitous accessory chalcopyrite (trace to 1%). Arsenopyrite, pyrite, and bismuthinite occur in minor amounts overall, but arsenopyrite is locally concentrated to >1%.

The SWZ is by far the most important zone of gold mineralization, by virtue of both its extent and grade. Gold is concentrated primarily within the laterally continuous, tabular skarn body developed along the upper contact of the major marble unit within the upper portion of the BMS. Subordinate gold mineralization occurs within a similar but less extensive skarn body developed along the marble unit's lower contact. These tabular bodies thicken and eventually merge down-dip (eastward) to form a single skarn mass. This region in which the marble unit `pinches out' has become known as the "nose". The NLF interrupts the SWZ along most of its strike extent.

The nature of the boundaries to the gold mineralized zone varies along its dip length. In the western (up-dip) portion, the entire thickness of skarn is mineralized and the zone boundaries are lithologic and sharp. The structural hanging wall is altered andesite (skarned mylonite or hornfels), and the footwall is marble.

As the skarn body thickens eastward a proportionally lesser thickness is mineralized, and the hanging wall boundary to gold mineralization becomes somewhat gradational, although concentrations generally decrease dramatically. The gold is concentrated towards the marble contact for much of the zone's dip length, but approaching the marble nose region it becomes concentrated towards the middle of the (thicker) skarn body. In this case both boundaries to the mineralized zone are arbitrary, with hangingwall and footwall lithologies consisting of poorly to unmineralized skarn.

Gold mineralization within the SWZ is more or less continuous along approximately 800ft of strike extent and 1,200ft down-dip. This zone extends 100ft to 150ft beyond the marble nose. Within these limits, there are three reasonably coherent sub-parallel grade-thickness trends oriented northeasterly (approximately along strike). These are evident from presentations of both drill hole and block-model calculated grade-thickness, and from modeled grade distribution in cross-section.

Gold tends to be concentrated in portions of the skarn distal to the southern appendage of the Buckhorn Mountain pluton. Average grades near the marble nose are lowest, while those of the western portion of the upper skarn unit away from the nose are highest. This is supported by grade distribution graphs and averaged drill hole-intercept grades of regional sample sub-populations of the SWZ.

The stratigraphic sequence that hosts the SWZ extends northward into the GB area west of the FMZ. In this area, gold mineralization occurs sporadically within SWZ-type pyroxene-dominant skarn developed adjacent to several distinct marble horizons. Although skarn here is relatively continuous, gold concentration is erratic.

Mineralization in the Gold Bowl.
Gold mineralization occurs throughout the large skarn mass of the GB, but the bulk of it is concentrated toward the FMZ in two distinct geological settings. Boundaries to mineralized zones within the GB skarn are generally gradational and in some cases were assigned arbitrarily.

The `floor' to the GB skarn mass is granodiorite of the Buckhorn Mountain Pluton. Nearest the intrusive, the skarn is magnetite and garnet rich, with local massive magnetite. This magnetite-rich skarn defines a synform whose western limb rests against the FMZ. Gold is concentrated toward the structural `top' of the unit, often overlapping the upward gradation to garnet dominant, magnetite-poor skarn. The geometry of the gold-bearing zone mimics that of the magnetite-rich skarn. Gold concentration in this magnetite skarn has the lowest grade among the four ore types. Locally massive concentrations of pyrrhotite are unrelated to gold mineralization.

The upper portion of the GB skarn mass consists of garnet dominant assemblages. Gold mineralization is primarily focused on a diorite body situated in the upper reaches of the garnet skarn, toward the FMZ. Portions of the body itself have been altered to garnet dominant endoskarn. Gold is concentrated adjacent to the diorite, mostly in its structural hangingwall, and locally within it. Controls on the distribution of gold are apparently complex, and the overall geometry of the broader diorite zone reflects this. Elsewhere, subordinate gold ?oncentration within garnet dominant skarn occurs as relatively narrow, ore or less stratabound zones lacking otherwise distinct geological associations. The diorite endoskarn is treated in this study as a distinct subset of the GB skarn.

Mineralization in the Andesite Zone.
Gold mineralization occurs in skarn altered zones within the andesitic volcanics, in the region between the SWZ and the main skarn mass of the GB. Skarn development is erratic in the andesite and is dominated by pyroxene. Gold concentration occurs in both skarn and adjacent hornfelsed andesite. Zones of gold concentration within the andesite are of generally low grade.



- subscription is required.

Mining Methods


- subscription is required.


Crushers and Mills

Milling equipment has not been reported.



- subscription is required.


All production numbers are expressed as metal in doré.

Operational metrics

Ore tonnes mined 189 kt438 kt369 kt
Tonnes processed 234 kt441 kt437 kt
Daily mining capacity 1,000 t
Daily milling capacity 2,100 t

Production Costs

Cash costs (sold) Gold Equivalent USD 477 / oz  


Capital expenditures M USD
Revenue M USD 96.3  
Operating Income M USD 43.4  
Gross profit M USD 58.9  

Heavy Mobile Equipment

Fleet data has not been reported.


Mine Management

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Jun 19, 2024

Aerial view:


- subscription is required.