Blewett Iron Mine, Peshastin Creek, Blewett Mining District (Peshastin Mining District), Chelan County, Washington, USAi

Regional Level Types
Blewett Iron Mine	Mine
Peshastin Creek	Creek
Blewett Mining District (Peshastin Mining District)	Area
Chelan County	County
Washington	State
USA	Country

A Fe-Ni-Cr deposit/mine located on a prominant ridge N of Shaser Creek at its junction with Peshastion Creek.

Several laterite deposits overlie serpentinized ultrmafic rocks of the Ingalls Complex, and underlie the Eocene Swauk formation.

This mine has not produced but has been extensively evaluated as an iron resource.

Tectonics: Several Iron-Nickel-Chromium Lateritic Deposits Overlie Serpentinized Ultramafic Rocks (Broughton, 1943, P.9-13) Of The Ingalls Complex, A Jurassic Ophiolite Complex (Miller, 1985, P. 27; Tabor And Others, 1982, P. 5-6). Cascade Volcanic Arc


Deposit: Iron deposits of the blewett area were evaluated in the 1940's by the washington division of geology. This was followed by extensive drilling by the u. S. Bureau of mines (10 holes, 2395 ft.) and metallurgical testing. (see references for specific reports.) this evaluation showed reserves of 46,000 tons at a grade of 0.88% ni, 2.5% cr2 o3, 32% fe, and 8,000,000 tons at a grade of 0.39% ni, 0.85% cr2 o3, and 11.53% Fe (huntting, 1956, p. 194). Deposit is a conglomerate of subangular to well-rounded pebbles, cobbles, and boulders of serpentinized peridotite embedded in a ferruginous and serpentinous matrix, plus scattered iron-rich lenses of finer nonconglomeritic materials. Fine-grained lenses and matrix of conglomerate are particles of magnetite, hemetite, serpentine, spinel, and chromite. Fine-grained lenses resemble matrix but are finer grained and contain much more hematite and magnetite. Dimensions are for principal iron-rich lens. Deposit locally cut by diabase dikes. Mrds records us53036, w017901 have been merged with this record and deleted. The deposit is generally thought to be a buried laterite. The blewett-cle elum iron-nickel zone is a discontinuous series of deposits along a 20 mile east-west trend.


Development: Econ.com: the blewett iron deposit has not produced but has been extensively evaluated As an iron resource (huntting, 1956, p. 194).


Geology: The laterites were transported and deposited beneath or As basal beds of the eocene swauk formation. Lamey(1950, p.1) tentatively interprets the conglomeratic iron beds As landslide debris or mudflow deposits. Deposit is considered an eastward extension of same iron formation As at cle elum, 25 mi to the west. Lamey (1950) believed that the deposit resulted from residual weathering of the underlying serpentinite. Ingalls complex is an ophiolite complex ; geol.desc: deposit overlies serpentine and underlies the swauk formation; it is locally cut by younger diabase dikes. Principal iron-rich lens in explored area is about 450 ft. Long, 35 ft. Wide, and extends downward for 450 ft. The deposit is generally thought to be a buried laterite. The blewett-cle elum iron-nickel zone is a discontinuous series of deposits along a 20 mile east-west trend.



Ore(s): The Blewett Iron Deposits Are Laterite Deposits. Many Of The Laterites Were Eroded From Their Nearby Source Area And Deposited Form A Sequence Of Conglomerates And Fine-Grained, Iron-Rich Beds. The Iron And Chromium Were From Iron In Silicate Minerals, Magnetite-Hematite, And Chromite Weathered From The Serpentinite. Nickel Is From Silicates Released During Laterization (Deep Weathering) Of The Serpentinite (Broughton, 1943, P. 10).The Deposit Is An Iron-Rich Conglomerate, Which, Like That At Cle Elum, Overlies Serpentine And Underlies The Swauk Formation. Deposit is considered an eastward extension of same iron formation As at cle elum, 25 mi to the west. Lamey (1950) believed that the deposit resulted from residual weathering of the underlying serpentinite. Ingalls complex is an ophiolite complex ; geol.desc: deposit overlies serpentine and underlies the swauk formation; it is locally cut by younger diabase dikes. Principal iron-rich lens in explored area is about 450 ft. Long, 35 ft. Wide, and extends downward for 450 ft.



Commodity: Principal iron-rich lens has an average composition of 32.65% of fe, 0.90% ni, 1.66% cr. The matrix of the conglomerate has average content of 18.11% fe, 0.52% ni, 0.88% cr. Cascade Volcanic Arc


Deposit type: Lateritic Ni


Rock formation(s): Ingalls Tectonic Complex
Swauk Formation;Ingalls Tectonic Complex

Other Databases

Link to USGS MRDS:	10203916
Link to USGS MRDS:	10068216
Link to USGS MRDS:	10055839

Other Regions, Features and Areas containing this locality

References