 | Washington Pass, Washington |
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GEOLOGY
Golden Horn Batholith - Tertiary. The Golden Horn Batholith is a highly evolved alkaline (Sodium rich) granite that contains a high concentration of REE (rare earth elements) and other incompatible elements (such as zirconium). During fractional crystallization of an evolving magma, the residual liquid became increasingly enriched in these incompatible elements as phases that were crystallizing rejected them from their structutre. 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 two of these rare mineral species, zektzerite, NaLiZrSi6O15, and the REE mineral, okanoganite- (Na,Ca)3(Y,Ce)12Si6B2O27F14. Over 50 mineral species have been identified at this locality.
Collecting is within the Okanogan National Forest. The host granite covers a vast area of of alpine terrain.
MINERALS (incomplete list) CLICK for COMPLETE LIST
| Na3(Fe,Mg)4(Fe,Al)Si8O22(OH)2 - Brilliant black prismatic crystals up to 3". Also found as inclusions within smoky quartz. | |
| (K,Na)3(fe,Mn)7Ti2Si8O24(O,OH)7 - Bronze micaceous bladed aggregates with metallic luster are found within some miarolitic cavities. Some smoky quartz crystals contain brilliant thin metallic-lustered red blades of astrophyllite. | |
| CeCO3(OH,F) - mm-scale orange prismatic hexagonal crystals. | |
| KAlSi3O8 - Miarolitic cavities lined with opaque white crystals to 1/2". | |
| (Na,Ca)3(Y,Ce)12Si6B2O27F14 - Rare small mm-scale tan to peach colored crystls in miarolitic cavities. | |
| SiO2 - Milky to smoky crystals line pockets. Crystals are up to nearly a foot in length and vary in quality. Some large gemmy quartz is smoky-amethyst. Inclusions of arfvedsonite, astrophyllite, or other species are common. | |
| Na2Fe+32Fe+23(Si8O22)(OH)2 - Acicular opaque dark blue-green cystals. Some riebeckite is absestiform. | |
| FeCO3 - mm-scale rhombohedra in miarolitic cavities. | |
| NaLiZrSi6O15 - white to gemmy pink crystals to 1". | |
| ZrSiO4 - Individual crystals to < 1/2" are found within some cavities. Specimens are brown, lusterous, and exhibit tetragonal prism faces. |
* photographed
Smoky
QUARTZ |
MICROCLINE, ARFVEDSONITE |
ZIRCON in miarolitic cavity |
Gemmy smoky QUARTZ |
Smoky QUARTZ |
ARFVEDSONITE |
MICROCLINE, ARFVEDSONITE |
ZEKTZERITE |
RIEBECKITE |
ZEKTZERITE |
OKANOGANITE, ZIRCON |
ARFVEDSONITE |
BASTNAESITE-(Ce) |
SIDERITE |
