Cottage Grove Native Copper Report
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- July 1, 1942 ~tate r.bepa7-tment of §eolo9J and cl1i(ine7-al flndu1-t'iie2 702 Woodlark Building Portland, Oregon COTTA.GE GROVE NATIVE COPPER La.ne County The occurrence of thin 1heet1 of native copper in the crack& ot an altered tuff has been proven by teat pits and drilling. While the copper itself 11 very pure, the percentage of copper in the tutf 11 not over 0.2%. Insufficient work h&a been done to demonstrate the econollic teuibllity ot working the deposit. B.C. M)rers, Di11ton ,Route, Cottage Grove, Oregon, purchasing on contract Owner: ,,,Y fro• John and Roy Walden, I. 12th Street, Eugene, Oregon. Location: S~¼ Bit sec. 19, T. 21 s., R.21., on Mosby Creek, about seven .Uea southeast of Cottage Grove. A!:!!,1 Deeded land, total acreage unknown. Histor:y: W.L. Cobb, Oak:l.SDd1 Oregon, traced the copper to th11 farm in August, 1940. The copper was first found in a dug well at a depth of 35'• ~ Kernan, of Roseburg, drilled two holes in the spring and summer or 1941 but work wa.a discontinued becauee the •copper ball.ad on the bit1" and stopped work. A 40 foot (?) abaft was 1unk near the old well and native copper was found. Another shaft, some distance east 1truck no copper. l,J.. Development: A dug well, depth 47 feet;,. r a shaft 4 tt. x 6 r;t 18 feet deep nearby~ another rrt .35 fJ\; deep, and two chUl't:l drill holes, dept.he 75 J\t:·· and 85 *~ Native copper was found 1n all except the 35 foot shaft to the east. Geology: The country rock in the immediate vicinity is a red, altered tuff, now clay like. When ~et, it is quite soft !i?ld plastic; when dry, it ia quite hard. At a higher elevation, and apparently overlying the - 702 Woodlark Building Portland, Oregon clayoid tuff is a much harder p;yroclastic. Heavy vegetation and aoil maeka moat of the bedrock so that no accurate data could be obtained on the attitude of the roclca but it is uauaed that th• cl.,-oid tuft ia fairly na.t and is overlain by harder pyroclaatice. Crack■ in the clayoid turf frequentl.7 contain th1n sheets ot native copper of exceptional purity. The ■ource or the copper is unlmo1111, but it ie auggeated that copper bearing 1olution1 percolated through .,,,Y'' the tuft and the copper wa.s depoai ted along the era.ck ■ bJ virtue of the reducing action or the clay. .Anal71i1 of the clay i teelt ahowa that it contain• 0.06 and o.u percent ot copper. There are no data on quantity. However, it ia reported that the native copper was found over a wide are~. The claf readil.7 alacks in water and recovery of the copper sheet■ should not be difficult. Report by: Ray C. Trea ■ her, (visited 6/15/42 with J'ohn~E• !llen). An~se, b7 R. G. Ba.Hett. ... COTTAGE GROVE COPPER PROSPECT Owner: Lessee: Salem, Oregon. Location: In the Oregon, about 7½ miles south of Cottage Grove on Mosby Creek. Histoq: Several years ago small flakes of native copper were discovered on the __M_j-~--~---- ranch in a water well which was being dug. Since that time several drill holes and one other shaft and a number of small open cuts ,..,Y have been dug to prospect for the "ore-bearing zone•. Miscellaneous: The valley of Mosby Creek is about½ mile wide at this point with a fairly level bottom and gently sloping mature valley walls. The property which is on the northwest side of a tributary running into Mosby Creek from the north runs along the foot of a ridge. The difference in elevation is less than 50 feet. Rainfall and climatic conditions are those typical of the upper Willamette Valley in Oregon. Development work: Development work at the present time consists of the following: one 47-foot well, one 37-foot well, 2 churn drill holes, 18-foot shaft, and two or three small open cuts. ~x(.6, Geology: The country rock consists of well-bedded, fine-grained red tuff (in which th; copper seams occur) overlain by coarse tuff breccia with" occasional included water worn boulders. This volcanic ser1e~ is nearly horizontal and probably belongs to 'the Calapooya formation (F.ocene ?) • o.t r~ ('l\ \}td, ¼- Since the shafts were inaccessible, the only place where the attitude I\ of the copper seams were visible was in the bed of the creek where they had m~- 4;i11..t~ a generalAstrike,~~---sg-:z,-..c-~""'ll and stood almost vertical. The sheets of copper occurring in these seams are rarely more than a millimeter in thickness and one or two centimeters in diameter. Commonly they are more or less completely • 1111 - 2 - altered to malachite. Mining and metallurgy: Samples were taken of the red t from Pit No. 4 and from the shaft near the upper outcrop. .06 and .11% copper respectively. In most of the open cuts no seams were visible., It was my impression that they are very local and restricted in both number and extent, prohibiting large-scale operation. However, since neither of CH- the shafts could be visited, this impression is not ltclusive. r ..... General Laboratory Number Date received .j"e-./?//1',;, Spectrographio Laboratory Number 'fd'S'" Sample received from ,f Q.UALITATIVE SPECTROGRAPHIO ANALYSIS (~uantities estimated to nearest power of ten) l. Elements present in concentrations over lo:f. 2. Elements present in concentrations 1oi - l~. · s-~· Elements present in concentrations 1~ - Oolt• ~ 4. Elements present in concentrations Ool'f .a .01'7:. r,· s. Elements present in concentrations .01~ ~ .OOlro Elements present in concentrations below .001~. ~I' ..+_,,... ~I V Dr. H. c. Harrisc>'n. Spectroscoplst • • • • • • 0 0 • • e • e O e • I e I .. General. Laboratory NWlber Date received Speotrographic Laboratory Number ;; .f_h'j'D..l Sample received from :✓.-£"'.Af'//t,~ ~ALITATIVE SPECTROGRAPHIO ANALYSIS (~uantities estimated to nearest power of ten) l. Elements present in concentrations over lO'f:. 4:_ 2. Elements present in concentrations 1oi m 11:. ft' Elements present in concentrations 1i - Oolfa• Elements present in concentrations Oolt "" oOlto 07;· s. Element.a present in concentrations oOl~ .. 00011:o -~"' M4-/ 4..7 6. Elements present in concentrations below .001~ • .,.,e( A~ ~ t1/ / Dr. H. c. Harridon. Spectroacopiet e • • • e 8 0 0 e • e • • e a • I e e ~ .3 CG-449 450 STATE DEPAR'IMENT OF GEOLOGY AND MINERAL INDUSTRIES ASSAY REPORT Grants Pass, Oregon Baker, Oregon Sample submitted by Ray Treasher Sample description: 42-!-4 red tu!f' trom upper outcrop. 42-!-5 red tuft from shaft near upper outcrop, The assay results recorded below are made without charge as provided by Chapter 176, Section 10, Oregon Laws 1937, the sender having complied with the provisions thereof. NOTICE: The assay results recorded below are tram a sample furnished by the above named person. This Department had no part in the taking of the sample and assmes no responsibiiity, oj;her than the accuracy ot the assay of the material as fur nished it by the sender. (Ou) GOLD SILVER uop)er Sample Ounces Ounces Total. Number per ton Value per ton Value Percent Value Percent-- Value Value 42-T-4 0.06 42-T-5 0.11 Market Quotations: Gold $ per oz. Silver J per oz. $ per lb. ·SAY7 t per lb. Assayer 2>·~ ~~-i \;;. ~ ' H· \\a ,j",: l.v"•·•·A,A,t,' ~., 0 I , BRIEF INFO:RMATION CONCERNING NATIVE COPPER IN STATE OF OR.11GON { . - ~-.;•· '-· \.L;l,t.A~A-·,1 LOCATION: This property is located seven and one-half miles from the main line of the Southern Pacific Railroad, on a good graveled road which has been used for years, near the Bohemia District, Lane County, Oregon. There are no hills or steep grades on this road as far as the property. It is practically a water grade route. The property is drained by a creek some fifty feet from bank to bank and by numerous small tributaries. It is believed that sufficient water can be obtained for a fair sized operation throughout the year. METHOD OF WOBK: This property is a stripping proposition. The overburden thus far known will average ten fe.et in thickness. The copper bearing rocks outcrop in two of the streams a]')ove mentioned so that in the valley floor, the overburden will be thin. The copper bearing rock is known to outcrop in a wide enough area to warrant the assertion that at least 80 acres are involved in the operation of an open pit mine on the property. It is quite probable that considerably more than 80 acres will eventually be included in the operations of this property. POWER AVAILABLE: Bonneville Electric Power is available at an airline distance of about ;r,. seven miles. Steam, gas, or electric shovels could be used in the operation for both stripping and mining the ore. THE COPPER BEARING ROCK: The rock containing the native copper is a'dark maroon to chocolate colored rbyolite; the dark color being due largely to the ~otting effect of the downward moving surface waters. This rbyolite was at one time a molten mass intruding into the country rock as a sill or lacolith. It did not come to the surface but remained under sufficient depth of burial to permit some crystallization of feldspar phenocrysts. The cooling was rapid enough to prevent these feldspar crystals from being pure. They almost invariably include some of the fine grained aphanitic ground mass of the rhyolite.