Porter Zone - 0530331239

Site Name

Primary: Porter Zone - 0530331239
Secondary: Clipper Zone
Secondary: Middle Fork Property
Secondary: Clipper Adit
Secondary: Snoqualmie River
Secondary: Condor Zone - 0530331241
Secondary: Hemlock Zone - 0530331240

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Commodity

Primary: Copper
Secondary: Silver
Secondary: Molybdenum
Secondary: Gold

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Location

State: Washington
County: King
District: Snoqualmie

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Land Status

Land ownership: National Forest
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.

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Holdings

Type: Private Lease
Type: Patented
Type: Located Claim

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Workings

Not available

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Ownership

Owner Name: National Resources Development Corp.
Percent: 100.0
Home Office: Washington
Info Year: 1977

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Production

Not available

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Deposit

Record Type: Deposit
Operation Category: Past Producer
Deposit Type: Porphyry copper
Operation Type: Underground
Mining Method: Unknown
Discovery Year: 1894
Years of Production:
Organization:
Significant: N

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Physiography

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

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Mineral Deposit Model

Model Name: Porphyry Cu

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Orebody

Not available

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Structure

Not available

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Alterations

Not available

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Rocks

Not available

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Analytical Data

Not available

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Materials

Ore: Molybdenite
Ore: Gold
Ore: Chalcopyrite
Trace: Silver

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Comments

Comment (Deposit): The Middle Fork Snoqualmie contains a series of mineralized highly fractured/brecciated zone along a NNE trend that are intersected by northwesterly trending fault zones. They may be part of one porphyry Cu (Mo) mineralizing event. Each highly fractured zone has a MRDS record. The records can found by searching for "Middle Fork Property" as a Grouping name in the Browser interface Advanced search. The location used is about in the middle of this fractured zone.

Comment (Deposit): From Thurber and others (1989, p. 94-97) The southwest part of the Middle Fork Snoqualmie River area, which includes the Porter, Hemlock, and Condor zones, is considered to have the greatest resource potential (fig. 9). The three zones are along or near the Copper Queen fault and the less well developed faults that intersect it. The Hemlock and Porter zones are believed to be contiguous and are discussed together. The 2380 adit is the main working level for the Hemlock zone. Surface sampling and shallow core holes in the Porter and Hemlock zones indicated areas of copper-rich rock as much as 85 ft (25.9 m) wide, mainly in northeast-trending structures. Drilling results in these zones show that the disseminated copper is mainly below the 3,200-ft (975-m) elevation. Two core drill holes, one from the surface outside the boundary of the Hemlock zone and one from underground in the 2795 adit (fig. 9), penetrated to 2,277-ft and 2,155-ft (694.0- and 656.8-m) elevations, respectively, in the downward projection of the Hemlock zone. Silicified rock and the disseminated sulfide minerals indicate that a deeper zone of copper-rich rock may exist at depth below the bottoms of the holes. Sampling and petrographic studies of rock from the 1,990-ft-long (606.7 m) 2380 arlit confirm the existence of copper there. The Hemlock breccia zone was penetrated from the portal of the adit to the 1,365-ft (416.1-m) point. From that point to the working face, another 625 ft (109.5 m), the rock becomes increasingly brecciated, altered, and mineralized, and the ratio of chalcopyrite to other sulfides becomes greater. Copper content of the wallrock averages approximately 0.44 percent from the 1,400-ft (426.7-m) point to the face and increases to 0.61 percent in the innermost 90 ft (27.4 m). Also, in the innermost 100 ft (30.5 m) of the adit, some 5-ft-long (1.5 m) samples contain as much as 1.14 percent copper. Samples from a 393-ft-Iong (119.8 m) crosscut driven (fig. 9) from the 2380 level toward the center of the Hemlock zone show an overall increase in copper values near the face. Samples taken from a 30-ft-long (9.1 m) interval between 338 and 368 ft (103.0 and 112.2 m) have a weighted average of 0.78 percent copper. The copper minerals and the rock alteration in the crosscut are similar to those in the 2380 adit. A comparison of the rocks observed on the surface of the Hemlock breccia zone with those found approximately 1,650 ft (503 m) vertically below in the workings shows a pronounced increase in intensity of alteration and in the amount of copper with depth. On the surface, intensely altered rock and copper sulfide minerals commonly occur only within or adjacent to fractures; whereas, at the 2380 level, alteration and copper mineralization have been pervasive through large volumes of the brecciated rock (fig. 10). A. R. Grant (written commun., 1971) observed that some large blocks of massive unaltered rock at the surface have graded vertically into mineralized and altered rock at the 2380 level. Further, because the eastern wall of the breccia zone dips steeply eastward, the area of the mineralized zone on the 2380 level is larger than on the surface. The core drilling program by a lessee in 1975 confirmed that the altered and copper-mineralized rock continues to lower elevations in the Hemlock breccia zone. The program explored the Hemlock zone to the 1,000-ft (305-m) elevation.

Comment (General): This deposit includes information from MRDS records describing the Condor-Hemlock, Clipper, and Three Brothers sites.

Comment (Geology): From Derkey and others (1990, p. 111, Condor-Hemlock) Of the numerous mineralized zones in the Middle Fork Snoqualmie system (Livingston, 1971, p. 152-153), the Condor-Hemlock contains the best demonstrated reserves. The deposit is open at depth (below 1,495 ft). The Condor-Hemlock zone is in the Snoqualmie batholith, northern phase granodiorite and tonalite that contains biotite and hornblende; locally it contains clinopyroxene. The rocks are light colored, medium crystalline, mostly equigranular with hypidiomorphic texture, and coarsely jointed. The northern phase is about 25 m.y. old, on the basis of interpretation of numerous discordant K-Ar ages of both hornblende and biotite (Frizzell and others, 1984, p. 18).The Condor-Hemlock is in a northwest-trending mineralized zone. The Condor is located at the center of the zone, and the Hemlock is located at the southeast end of the zone. The mineralization is in shear zones, along fractures, and in veins in granodiorite and tonalite. Hydrothermal alteration grades from propylitic at the surface to quartz-sericite-chlorite to K-feldspar predominating at depth. Pyrrhotite increases and pyrite decreases with depth.

Comment (Reserve-Resource): From Derkey and others (1990, p. 111, Condor-Hemlock) Secondary enrichment of covellite and chalcocite was found in a drill hole when the West Condor fault was intercepted between 151 ft and 203 ft. This 52-ft intercept averaged 1.66 % Cu, more than 1.0 oz/ton Ag, and $0.75 gold per ton (November 15, 1965 prices). The mineralized zone has a strike length of 1,000 feet, a thickness of 400 feet, and a depth of more than 400 feet. The Condor portion of the zone has potential reserves of 25-30 million tons averaging 0.616 % Cu and 0.032 % MoS2. Gold and silver values range from $0.40 to $1.25 per ton (October 1967 prices). The Hemlock zone (including part of another zone called the Porter and some adjacent zones) has been tested by 23 drill holes (total footage unknown) and three adits totalling 3,200 feet. By 1975, potential reserves of 91 million tons averaging 0.6-0.8% Cu and 0.02-0.05% MoS2 in the combined Porter and Hemlock zones was indicated (Gualtieri and others, 1975).

Comment (General): From Derkey and others (1990, p. 111, Condor-Hemlock) Both patented and unpatented claims are owned (1990) by United Cascade Mining Company, Inc. The deposit was explored by Anaconda Copper Co., Howe Sound Co., Climax Molybdenum Corp., Anaconda Co., Bear Creek Mining Co., Cities Services Minerals Corp., Westland Mines Ltd., Natural Resources Development Corp., Houston Oil and Minerals, and Electras Resources.

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References

Reference (Deposit): H. K. THURBER, MICHAEL S. MILLER, AREL B. MCMAHAN, and FRANK E. FEDERSPIEL, 1989, ECONOMIC APPRAISAL OF THE ALPINE LAKES STUDY AREA AND ADDITIONS, WASHINGTON, in U.S. GEOLOGICAL SURVEY and U.S. BUREAU OF MINES, Mineral Resources of the Alpine Lakes Study Area and Additions, Chelan, King, and Kittitas Counties, Washington: U.S. GEOLOGICAL SURVEY BULLETIN 1542-E, P. 94-97.

Reference (Deposit): LIVINGSTON, V.E., JR., 1971, GEOLOGY AND MINERAL RESOURCES OF KING COUNTY, WASHINGTON: WASHINGTON DIVISION OF MINES AND GEOLOGY BULLETIN 63, 200 P., 8 PL., (P. 152-153.)

Reference (Deposit): HUNTTING, M. T., 1956, INVENTORY OF WASHINGTON MINERALS-PART II, METALLIC MINERALS: WASHINGTON DIVISION OF MINES AND GEOLOGY BULLETIN 37, V. 1, 428 P., (P. 58).

Reference (Deposit): Patton, T.C., Grant, A.R. and Cheney, E.S., 1973, Hydrothermal alteration at the Middle Fork copper prospect, central Cascades, Washington; Economic Geology, v. 68, p. 816-830.

Reference (Deposit): Derkey, R.E., Joseph, N.L., and Lasmanis, Raymond, 1990, Metal mines of Washington - Preliminary report: Washington Division of Geology and Earth Resources Open File Report 90-18, p. 111-112.

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