DENNY MOUNTAIN SKARN
near North Bend, King County, Washington, USA

LOCALITY IMAGES


GEOLOGY
Skarn Deposit, periphery of Snoqualmie Batholith - late Oligocene to early Miocene (28 Ma[million years ago] to 22 Ma).

The Denny Mountain skarn (tactite) deposit is exposed in a deep canyon drainage that flows into Denny Creek. The skarn formed by metasomatism of Jurassic/Triassic age sedimentary rocks during intrusion of the Snoqualmie Batholith.

MINERALS (incomplete list) CLICK for COMPLETE LIST
*Calcite-
CaCO3 - Massive cystals fill mineralized voids. Etching away the massive calcite often reveals well-preserved mineral species that cystallized before the calcite.
*Epidote-
Ca2Al3Si3O12(OH) - Occurs as aesthetic fan-like acicular sprays to 10 centimeters.
*Garnet(Grossular)-
Ca3Al2Si3O12 - Occurs as translucent to opaque brownish-red dodecohedra.
*Hedenbergite-
CaFe2+Si2O5 - Radial aggregates of light brownish-green prismatic crystal (visual identification, not confirmed by laboratory analysis)
*Hematite-
Fe2O3 - Occurs as massive platey aggregates of lustrous silver crystals and as terminated rosettes, typically enclosed in calcite. Also occurs as mm-scale red and silver inclusions in quartz crystals ("raspberry" scepters).
*Orthoclase(Adularia)-
KAlSi3O8 - Occurs as sharp white cystals to about 2 cm with grossular garnet.
*Quartz-
SiO2 - Occurs as crystals of varying size, quality and habits. Japan-law twins and raspberry scepters (quartz with worm-like lepidocrosite inclusrions) are highly sought after by collectors.
*Scheelite-
CaWO4 - Occurs as mm-scale golden-yellow pseudo-octahedron associated with other skarn mineralogy. Crystals fluoresce blue under short-wave ultraviolet light.
* photographed
 
Grossular GARNET  
and
CALCITE
 
HEDENBERGITE
 
HEMATITE rose

 
EPIDOTE, QUARTZ
 
QUARTZ  with chlorite inclusions
and red
 GROSSULAR  garnet

 
Raspberry QUARTZ  scepter
with
 HEMATITE  inclusions and rosettes
 
Raspberry QUARTZ  scepter cluster
with
 HEMATITE inclusions
 
Raspberry QUARTZ  (Var: Amethyst) scepter
with
 HEMATITE inclusions

John Lindell Collection

 
Raspberry QUARTZ  scepter
with
 HEMATITE inclusions
 
Raspberry QUARTZ  scepter cluster
with
 HEMATITE inclusions
 
QUARTZ with HEMATITE

 
Double-terminated
Japan-law twin
QUARTZ
 
Japan-law twin QUARTZ
 
Sceptered QUARTZ

 
Botryodal blue OPAL
John Lindell Collection
 
SCHEELITE
 
ORTHOCLASE
(ADULARIA)



REFERENCES
(Under Construction)