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 (complete list) CLICK for PHOTOGRAPHED
  Actinolite (Byssolite)- Ca2(Mg,Fe)5(Si8O22)(OH)2
*Calcite- CaCO3
  Diopside- (Ca,Mg)SiO3
*Epidote- Ca2Al3Si3O12(OH)
*Garnet (Grossular)- Ca3Al2Si3O12
  Goethite- FeO(OH)
*Hedenbergite- CaFe2+Si2O5
*Hematite- Fe2O3
*Malachite- Cu2CO3(OH)2
*Orthoclase (Adularia)- KAlSi3O8
  Pyrite- FeS2
*Quartz- SiO2
*Scheelite- CaWO4
*Sericite- KAl2(AlSi3O10)(OH)2
* photographed
*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).
*Malachite-
Cu2(CO3)(OH)2 - Small radiating acicular clusters have been found.
*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.
*Sericite-
KAl2(AlSi3O10)(OH)2 - Occurs as clusters of micro rosettes, possibly pseudomorphing epidote sprays.
* photographed

 
EPIDOTE, QUARTZ
 
MALACHITE
Photo Copyright © Eli Hess 2020
 
QUARTZ  with chlorite inclusions
and red GROSSULAR garnet

 
Raspberry QUARTZ  scepter
with HEMATITE inclusions
Photo Copyright © Eli Hess 2023

 
Raspberry QUARTZ  scepter cluster
with HEMATITE inclusions

 
Raspberry QUARTZ  scepter
with HEMATITE  inclusions and rosettes
 
Raspberry QUARTZ  (Var: Amethyst) scepter
with HEMATITE inclusions
John Lindell Collection
 
QUARTZ with HEMATITE
Photo Copyright © Rick Dillhoff
John Lindell Collection

 
Raspberry QUARTZ  scepter
with HEMATITE inclusions
 
Raspberry QUARTZ  scepter cluster
with HEMATITE inclusions
Photo Copyright © Rick Dillhoff 2008
Lou Landers Collection

 
Double-terminated
Japan-law twin QUARTZ
Photo Copyright © Rick Dillhoff
Rick Dillhoff Collection
 
Japan-law twin QUARTZ
Photo Copyright © Rick Dillhoff 2008
Lou Landers Collection
 
Japan-law twin QUARTZ cluster with PYRITE

 
QUARTZ cluster with three-eared Japan-law twin
Photo Copyright © Eli Hess
Eli Hess Collection

 
CHRYSOCOLLA coating Japan-law twin QUARTZ
Eli Hess Collection

 
QUARTZ (slightly sceptered) with HEMATITE



 
Sceptered QUARTZ
Photo Copyright © Bohemia Aj
 
CHLORITE included QUARTZ
with SIDERITE
Eli Hess Collection

 
QUARTZ (double-terminated)
Photo Copyright © Eli Hess 2020
Eli Hess Collection

 
SERICITE pseudomorph after EPIDOTE?
with small crystals of QUARTZ
 
Botryodal blue OPAL
John Lindell Collection
 
ORTHOCLASE
(ADULARIA)

 
SCHEELITE
 
SCHEELITE
Photo Copyright © Eli Hess 2020
Eli Hess Collection


REFERENCES
 (Under Construction)