GOLDEN HORN BATHOLITH
Washington Pass, Okanogan County, Washington, USA

LOCALITY IMAGES


GEOLOGY
Golden Horn Batholith - Tertiary period, Eocene epoch - (49 millions of years before present). The Golden Horn Batholith is a highly evolved alkaline (sodium-rich) granite that hosts a suite of rare minerals. About 50 million years ago, the magma that formed the batholith cooled and the rock-forming minerals began to crystallize. Through the process of fractional crystallization, the residual liquid became increasingly enriched in incompatible elements (such as lithium, zirconium, and the REE (rare earth elements)) as the rock-forming mineral phases that were crystallizing rejected them. Late stage volatile rich fluids carrying this highly fractionated chemistry precipitated a suite of rare minerals in miarolitic cavities within the alkaline granite. The Golden Horn Batholith is the type locality for three of these rare mineral species, zektzerite- NaLiZrSi6O15, the REE mineral, okanoganite- (Na,Ca)3(Y,Ce)12Si6B2O27F14 and calciohilairite- CaZr[SiO 3]3·3H2O. Over 50 mineral species have been identified at this locality, with a great potential for new mineral discoveries.

Collecting is within the Okanogan National Forest. The host granite covers a vast area of of alpine terrain.

MINERALS (complete list - based off of mindat.org, Golden Horn Batholith page)
CLICK for PHOTOGRAPHED

   Aegirine
   Aenigmatite
   Agardite-(Y)
   Albite
   Allanite-(Ce)
   Anatase
*Arfvedsonite
*Astrophyllite
*Bastnäsite-(Ce)
   Biotite
   Calciohilairite
   Calcite
   'Ca-Catapleiite'
   Cerussite
   Chamosite
   Chevkinite-(Ce)
   Chrysocolla
   Clinochlore
   Elpidite
   Epidote
   Euxenite-(Y)
   Fayalite
   Fergusonite-beta-(Y)
    Ferrohornblende
   Ferrorichterite
   Fluorite
   *Gadolinite-(Y)
   Gagarinite-(Y)
   Galena
   *Genthelvite
   Goethite
   Hematite
   Kainosite-(Y)
   Löllingite
   Magnetite
   Malachite
   Masutomilite
*Microcline
   Molybdenite
   Monazite-(Ce)
*Okanoganite-(Y)
   Orthoclase
   Parisite-(Ce)
   Pharmacosiderite
   Polylithionite
   Prehnite
   Pyrite
*Quartz
*Riebeckite
   Scorodite
*Siderite
   Sogdianite
   Sphalerite
   Synchysite-(Ce)
   Thorianite
   Titanite
   Wulfenite
   Xenotime-(Y)
*Zektzerite
*Zircon

* photographed
 
ARFVEDSONITE

 
BASTNAESITE-(Ce)
perched on
ZIRCON
 
BASTNAESITE-(Ce)
Photo Copyright © Saul Krotki 2005
 
BASTNAESITE-(Ce)
(not confirmed)

 
CALCIOHILAIRITE
 
GADOLINITE-(Ce)
Photo Copyright © Saul Krotki 2009
 
GENTHELVITE
Photo Copyright © Saul Krotki 2008

 
MICROCLINE,
ARFVEDSONITE


 
OKANOGANITE,
ZIRCON

Photo Copyright © Saul Krotki 2006
 
OKANOGANITE (fourling twin)

 
Gemmy smoky
QUARTZ
 
Smoky QUARTZ
with
ARFVEDSONITE
inclusions
 
Smoky QUARTZ
with ASTROPHYLLITE  
inclusion

 
RIEBECKITE

 
SIDERITE
 
ZEKTZERITE

 
ZEKTZERITE
 
largest known
ZEKTZERITE
 
ZIRCON
in miarolitic cavity

OTHER RESOURCES

Becker, Randy, 1991, Minerals of the Golden Horn Batholith, Okanogan County, Washington, Rocks & Minerals, v. 66, no. 6, 450-459.