Mount Si

The Mount Si is a copper mine located in King county, Washington at an elevation of 4,239 feet.

About the MRDS Data:

All mine locations were obtained from the USGS Mineral Resources Data System. The locations and other information in this database have not been verified for accuracy. It should be assumed that all mines are on private property.

Mine Info

Name: Mount Si

State:  Washington

County:  King

Elevation: 4,239 Feet (1,292 Meters)

Commodity: Copper

Lat, Long: 47.51361, -121.70500

Map: View on Google Maps

Satelite View

MRDS mine locations are often very general, and in some cases are incorrect. Some mine remains have been covered or removed by modern industrial activity or by development of things like housing. The satellite view offers a quick glimpse as to whether the MRDS location corresponds to visible mine remains.


Satelite image of the Mount Si

Mount Si MRDS details

Site Name

Primary: Mount Si
Secondary: Bald Hornet Claims


Commodity

Primary: Copper


Location

State: Washington
County: King


Land Status

Land ownership: Private
Note: the land ownership field only identifies whether the area the mine is in is generally on public lands like Forest Service or BLM land, or if it is in an area that is generally private property. It does not definitively identify property status, nor does it indicate claim status or whether an area is open to prospecting. Always respect private property.


Holdings

Not available


Workings

Not available


Ownership

Owner Name: Weyerhaeuser Co.
Years: 1991 -

Owner Name: Duval Corp. (1970'S)


Production

Not available


Deposit

Record Type: Site
Operation Category: Occurrence
Operation Type: Unknown
Years of Production:
Organization:
Significant: N
Deposit Size: S


Physiography

General Physiographic Area: Pacific Mountain System
Physiographic Province: Cascade-Sierra Mountains
Physiographic Section: Northern Cascade Mountains


Mineral Deposit Model

Not available


Orebody

Form: BRECCIA


Structure

Not available


Alterations

Alteration Type: L
Alteration Text: Plutonic Rocks Intensely Sericitized (Phyllic)


Rocks

Name: Diorite
Role: Associated
Age Type: Associated Rock
Age Young: Miocene

Name: Diorite
Role: Associated
Age Type: Host Rock
Age Young: Holocene

Name: Diorite
Role: Associated
Age Type: Host Rock Unit
Age Young: Holocene

Name: Diorite
Role: Associated
Age Type: Associated Rock Unit
Age Young: Miocene


Analytical Data

Not available


Materials

Ore: Pyrite
Ore: Chalcopyrite
Gangue: Sericite
Gangue: Quartz
Gangue: Tourmaline


Comments

Comment (Location): MINERALIZED AREA IS EAST OF SUMMIT OF MOUNT SI. LOCATION GIVEN IS FOR TOURMALINE BRECCIA

Comment (Deposit): DEPOSIT HAS BEEN GIVEN THE INFORMAL NAME OF A BRECCIA PIPE CU DEPOSIT, FOR WHICH THERE IS NO PUBLISHED MODEL. QUARTZ-PYRITE-TOURMALINE VEINLETS. TOURMALINE VEINLETS ARE CUT BY LATER QUARTZ VEINLETS. TOURMALINE BRECCIA LOOKS LIKE COLLAPSE FEATURE IN HORNFELS. THERE ARE SEVERAL BRECCIA BODIES IN AREA

Comment (Workings): 15 WINKIE HOLES TOTALLING 1,500 FT, SOIL SAMPLING PROGRAM

Comment (Geology): HORNFELS PROTOLITH MAY HAVE BEEN PRE-TERT QUARTZITE AND SEDIMENTARY ROCKS


References

Reference (Deposit): ASHLEY, R.P., 1991, FIELD EXAM WITH GRANT NEWPORT OF WEYERHAUSER

Reference (Deposit): TABOR, R.W., FRIZZELL, V.A., JR., BOOTH, D.B., WHETTEN, J.T., WAITT, R.B., JR., AND ZARTMAN, R.E., 1982, PRELIMINARY GEOLOGIC MAP OF THE SKYKOMISH RIVER 1:100,000 QUADRANGLE, WASHINGTON: U.S. GEOLOGICAL SURVEY OPEN-FILE REPORT 82-747, SCALE 1:100,000.


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