The Gold Quartz Veins of the Julian District, California Citation Sandberg, Edward Charles (1929) The Gold Quartz Veins of the Julian District, California. Master's thesis, California Institute of Technology. doi:10.7907/my86-r714. https://resolver.caltech.edu/CaltechTHESIS:08192024-221334740 Abstract No abstract. Item Type: Thesis (Master's thesis) Subject Keywords: (Geology) Degree Grantor: California Institute of Technology Division: Geological and Planetary Sciences Major Option: Geology Thesis Availability: Public (worldwide access) Research Advisor(s): Ransome, Frederick Leslie Thesis Committee: Unknown, Unknown Defense Date: 1 January 1929 Record Number: CaltechTHESIS:08192024-221334740 Persistent URL: https://resolver.caltech.edu/CaltechTHESIS:08192024-221334740 DOI: 10.7907/my86-r714 Default Usage Policy: No commercial reproduction, distribution, display or performance rights in this work are provided. ID Code: 16652 Collection: CaltechTHESIS Deposited By: Benjamin Perez Deposited On: 20 Aug 2024 20:41 Last Modified: 20 Aug 2024 20:47 Thesis Files PDF - Final Version See Usage Policy. 13MB Repository Staff Only: item control page

OF THE GOLD QUARTZ VEINS JULI.AN CALIFORW IA IJ.1rIE DISTRiCT, by Edwn.rd Charles Sandberg A THESIS IN PARTIAL FULFILLMENT OF THE THE DEGREE CALIFOiniIA REQUIREMENTS FOR OF MASTER OF SCIENCE INSTITUTE PASADENA, OF TECHNOLOGY CALIFOlUHA 1929 TABLE OF CONTENTS Introduction and Acknowledeement- - - - - - 1 Location and Accessibility- - 1 Climate and Vegetation- - 2 Bibliography- - - 3 Geology - - - - - - - - - - 4 Rock Formations- - 5 Julian Schist Series- - - - - 5 Stonewall Quartz Diorite- - 7 Cu.ya.maca Basic Intrusives - - - - 7 Alluvium- - 8 Physiography - - - - - - 8 -10 Structure-~ - Geologic History - Economic Geology- - - History of Mining- - - - - - - - - - - -11 - - -13 - - - - -13 Gold Quartz Veins- - -14 General Character - - - - - -18 Mineralogy Ore MineralsGa.ngu.e Minerals - -19 - -19 - - - - - - - - - - -20 Para.genesis- - - - - -20 Genesis- - - - - - - -21 TABLE OF CONTENTS (continu.ed) Placers- - - - - - - - - - - - - - - - - -22 Conclusions and Practical Deductions - - - - -23 }Aines- - - - - - - - - - - - - - - - - - 25 ILLUSTRNJ.1 Ions Fig . 1. Index map- - - - 2 2. Geologic map - - 5 3. Table showing distribution of minerals - - -20 4. Paragenesis- - - - - - - - - 5. Section of Quartz lens es - - - - - - - - - -25 6. Section of folded vein - - - - -26 7. Longitudinal section of Chariot mine - -25 Plat es I to VII at end. of report. - - -21 1. Introduction and Acknowledgement The gold veins of the Julian district, which includes also the Banner district, are of interest for numerous reasons. First, on account of richness of the ore in various localities particularly the upper workings of the mines. Second, the apparently capricious distribution of small high grade ore shoots and the abruptness of the transition from these shoots to nearly barren quartz. Third, the causal relation that exists between the general structure of the region and the gold veins. The report is the result of four weeks of field work carried on in the spring of 1929. At that time the gold veins were mapped and geolog- ical data was obtained. The topographic map used for this region was the United States Geological Survey's Ramona topographic sheet enlarged four times. The original map was surveyed i n .1901 on the scale of two miles to the inch with a 100 foot contour interval. Grateful acknowledgements are due Mr. c. A. Ferrin of the Golden Chariot Mining Corporation for the privilege of examining the property. To Mr. G. Surprenaut, superintendent of the North Huboard Mining Company, Mr. A. Frary and Mr. Tom Strick of Julian, and many other people of the region, acknowledgements are ma.de for information, hospitality, and courtesy. The writer is especially indebted to Professor F. L. Ransome for advice and helpful criticism during the completion of the report, and to Mr. Rene Engel for pointing out fruitful lines of investigation. Location and Accessibility The district lies within the ma.in mountainous range of San Diego L Fig Jr'" Mo. County. It is situated in the northeastern part of the ~amaca regi on which embraces the Cuyamaca mountains. It is bounded on the north by Volcan mountain, on the east by San Felipe valley, and on the southeast by Granite mountain. Juliiin is located on the drainage divide between the Sa lton sea and the Pacific ocean. It has a population of 115 and is the most important habitation in the region. The town of Banner, which is seven miles south- east of Julian at the foot of Banner brade, now cont a ins less than a dozen residents. Both towns were once thriving mining centers, having bet- ween the years 1870 and 1882 a population of approximately 700 inhabitants for Julian and 300 for Banner. At present Julian is important as a trade center for farmers from nearby valleys. It is located sixty miles northeast of SEa.n Diego by county road v,hich is traversed clai ly by busses. 11he old road fror.i Julian to Banner, shown on the United States Geological Survey sheet, has been abandoned. r he road now in use has been plotted on the map by the writer. Climate and Vegetation '.l:he range in relief generally is great, especially in Banner and Chariot canyons, although in the immediate vicinity of Julian the country is a gently rolling upland. The elevation of Julian is 4200 feet and of Banner 2700 feet. Around Julian there is an open growth of pines, oaks, and manzanita with, in places a dense growth of chaparral. On the slopes of Banner and Chariot canyons the trees disappear and chaparral covers most of the area. · From Ban...~er to San Felipe Valley the vegetation becomes somewhat more scanty and takes on a desert-like appearance. I The average precipitation in the region around Julian is 29.02 I u. s. G. s. Water Supply Paper 446. inches while at Banner it is said to be about 12 inches. The maximum precipitation occurs du.ring the winter months although there are occasional swnmer showers. Du.ring the rainy season the road between Julian and Banner is difficult to traverse but is seldom impassable. Water is obtained in the region from wells, springs, and streams, but the latter are generally dry in the aummer season. In the early days the timber used for mining operations was principally derived from the vicinity of Julian and the adjacent mountains, but at the present time it is shipped from San Diego. BibliogTaphy The number of publications on the Julian District is not large. The only previous systematic account of the geology is that by F. s. Hudson, who gave the gold veins only a cursory examination. The annual reports of the State Mining Bureau, particularly the reports of 1888, 1889, 1890, 1892, and 1914, record the facts concerning the properties, equipment, and geology in a general way. The following list contains the principal references found. 1886. Hanks, H. G., Sixth Annual Report of the State Mineralogist, part I, for year ending June 1, 1886, pp. 80-90. 1889. Goodyear, w. A., Ninth Annual Report of the State Mineral- ogist for the year ending Dec. 1, 1889, pp. 142-147. 4. 1890. Preston, E. B., Tenth Annual Report of the State Mineral- ogist for the year ending Dec. 1, 1890, pp. 540-44. 1892. Storms, w. H., Eleventh Annual Report of the State Mineral- ogist for two years ending 1892, pp. 376-381. 1893. Fairbanks, H. W., Geology of San Diego; also portions of Orange and San Bernardino Counties. State Mineralogist, pp. 76-120. 1894. Eleventh Annual Report of the Map (1893.) Fairbanks, H. w., A Remarkable Folded Vein in the Ready Relief Mine, (Banner District, San Diego County, Calif.) Eng. M. J. vol. 57, pp. 321-322. 1896. Storms, W. H., Thirteenth Annual Report of the State Miner- alogist 6or the two years ending Sept. 15, 1896, pp. 331-346. 1914. Merrill, F. J. H., Geology and Mineral Resources of San Diego and Imperial Counties. 1922. Calif. State Min. Bureau. pp. 23-30. Hudson, F. s., Geology of the Cuyaroaca Region of California, with Special Reference to the Origin of the Nickeliferous Pyrrhotite. Univ. of Calif. Pub. in Geology, vol. 13, no. 6, pp. 175-252. Geology Su.rrunaryi- The geologic map (fig. 2) of the region surrounding the 'l.. Julian District is taken largely from Hudson's geological report of the ~ Hudson, F. S., Geology of the Cu.ya.maca Region of California. Univ. of Calif. Pub. vol. 13, no. 6, pp. 175-252, 1922. Cuyamaca region. Hudson's boundaries have been verified by the writer who has in addition traced out and mapped the gold veins. The oldest rocks in the district are schists of undetermined age, 5. which are presumably of the same age as the other schists in the peninsular range and may be of the same age as, or older than, the slates of the Santa Ana mountains, which are Triassic. These schists are intruded by a quartz diorite which is part of the peninsular batholith and is probably equivalent to the post-Mariposa intrusion of the Sierra Nevada. Basic intrusives of norite, gabbro, and basic diorite intrude the quartz diorite and occupy a considerable area in the vicinity of the Cuyamaca mountains. Dikes of pegmatite and aplite occur cutting both schist and quartz diorite, and basic rocks. Open valleys with flat rolling surfaces occur in the region around Julian and Cu.yamaca mountain and are unde~lain by alluvium which is at the present time being removed by streams. In San Felipe valley both alluvium and lake beds occur. Rock Formations Julian Schist Series:- This seri es has been ably described in de- tail by Hudson, so that only a short resume will be given. The schist series extends through the district in a general north-south direction and varies in width from three-quarters to a mile and a half. Small isolated mas ses of schist are found outcropping in the quartz diorite suxrou.nding the main mass. The centra l pertion of the main body of Julian schist is made up of a fine grained, fissile, quartz-muscovite-biotite schist. Intercal- ated within the schist series are found beds of bluish dense fine-grained quartzite. In many places it is associated with the quartz veins, partic- ularly with the branch vein that runs between the Chariot and Ready Relief GEOLOGIC MAP OF JULIAN DISTRICT CALIF. - ~( -~ Zc~, 6 :· ..,,. ; D ·- ,,,: :: ..,.,.., □ -~ All\Mvm I E] ,'!::f/: I R. 4 □ ( ----- E. I --- llef30 4 . Helvet;a 5 Shamrock 6 . C.nc,nna"tt; Bel I EJ 7 Janet 0 . San D:ego 9. Tom Scott I 0 . Chapparal 11. Wa,-loc: k 12. Ant.,lope 13. Me.dd,m 14. Kentvck 5 . E1 Fault Topogi-aphy From US.GS. S h.,.,t r7J ll:__iJ LIST OF MINES I Wa11h;ngton i . O-ns 3. Ea le St.CT\ON AA ... Volca-n M • · SW sooo' qooo 15 Redman 2 000 16. ~eady Rel,ef \000 17 Hubbard 15. Ella 19. Golden Chanot 20. Ranchaa 21 . Frid• (N;ckel) 0 .Julian 5 ch~t ~ ~ 5tonew-.ll CuyAm-.ca Quu·h D,or,te ea••• RI<,._ 6. veins about one-third of a mile south of Banner. On the western border of the schist body there is a zone of coarse schists and pa.ragneisses. The writer observed that the coarse schists in many places were conglomeratic in texture. Associated with the gna.rly schists a.nd gneisses on the border zone are found short lenses of quartzose rock. Near Cuyamaca. reservoir in a few places are found sillimanite- qµartz-mica gneiss with some tourmaline and andalusite-bearing gneiss. Injection gneisses of varying composition are prevalent on the eastern border of the schist body and are made up in part of material of igneous or pegmatitic nature. Some of the injection gneisses contain tour- maline, sillimanite, andalusite, and coarse crystals of mica. Subordinate layers of amphiboli te schist and actinoli te schist are found intercalated in the schist series. Actinolite schist is found at the Helvetia mine, while near Banner the amphibolite schist is found in a few isolated places. The actinolite schists are presumably derived from andesitic or basaltic volcanic rocks. In a specimen of the folded vein at the Hollywood mine examined by the writer, a small amount of apatite was found associated with the schist. As to origin, Hudson says: "The Julian schists are the product of metamorphism of a series of shales, fine clayey sandstones, and nearly pure quartz sandstones, with subordlnate layers of basic volcanic rocks. In the less metamorphosed portions the schistosity is parallel to the original bedding of the rock. ln the intensely metamorphosed portions there is evidence of two directions of schistosity, the earlier conforming to the original bedding, the later at a varying angle to it. The rocks exhibiting the double schist- 9sity, are characterized by peculiar minerals generally ascribed to con- 7. tact metamorphic action, i.e., sillimanite and andalusite. The intrusive quartz diorite is without doubt responsible for these contact minerals. There seems some reason, therefore, to attribute the later schistosity to the action of the intrusion. Further evidence that the rocks were schistose before the int rusion of the quartz diorite is found in the extensive development of lit-par-lit injection gneisses and the total absence of hornfels along the contacts." Stonewall Quartz Diorite:- This rock, in the vicinity of Julian is typical of the plutonic rocks tha·t are so widespread throughout the mountainous portion of San Diego County. There the intrusive is a quartz diorite cut by a number of acidic and basic dikes, which a.re found in greater proportion in the vicinity of Volcan mountain east of Julian and near Granite mountain southeast of Banner. A petrographic description of the quartz diorite has been ma.de by Hudson, as follows: "These rocks are medium to coarse grained aggregates of quartz, plagioclase, biotite, and rarely orthoclase. The plagioclase varies from albite to a.ndesine, and in one specimen from a d&rk segregation, it is labra.dorite. Green hornblende occurs in dark segregations. Ortho- clase is :present in only three out of fourteen specimens examined and in these makes up less than ten percent of the rock." The g_uartz diori te has a gneissoid character near the schist conta,ct. The strike of the gneissoid structure is in general parallel to the neighboring schist and represents flow lines of a partially consolidated magma. Cuyamaca Basic Intrusives:- These rocks, which are ma.de up of gab- bros, norites, and basic diori"tes, are described in detail by Hudson. 8. They lie west of the Julian schist belt and are of particular interest because of the occurence of nickeliferous pyrrhotite in norite at the Friday mine. The amount of nickel found has been of little economic va.lue,but is of scientific interest. Alluvium:- The alluvium in San Felipe Valley consists of unconsol- idated rock debris, ,sand, and clay. In the southeastern part of the valley San Felipe creek and the road both cut the valley fill. The banks show evenly stratified fine sands containing great quantities of mica 3 and considerable clay. • Lee suggests the possibility that this part of 3 Lee, c. H., U. s. G. s. ~'iater Supply Paper 446, p. 207. the valley is occupied ·by lake beds. No direct evidence was obtained by the writer as to the verity of this theory. In the valleys situated in the open rolling country of Julian considerable thicknesses of bedded, unconsolidated, sandy alluvium are exposed as a result of stream cutting. Physiography The Julian district embodies two distinct physiographic features. In the vicinity of Julian, Cuyamaca Lake, and westward, the topography is a gently rolling surface floored by residual soil. East and southeast of these rolling tracts toward Banner canyon and San Felipe Valley there is a belt characterized by deeply dissected canyons with valleys separated by parallel mountain ranges. A few mountain peaks such as North Peak (6,028), Middle Peak (5,750) and Cu.yamaca Peak (6,515), project above the gently -rolling surface. These isolated mountain peaks have been regarded as due principally to erosion. It is believed that the land prior to the elevation was a pene- 4 plain. As the land w~s raised the streams were rejuvenated and cut their 9. 4' Fairbanks, H. w., The Physiography of California. Am. Bur. Geog. Bull., vol. 2, pp. 2;52-252, 329-350, 1901. valleys to their present depth. Faulting has contributed largely to the topography of the region east and southeast of Julian . to a fault. Banner canyon owes its origin principally 5' On the fault map of Cal i fornia, San Felipe Valley and the S' Fault Map of the State of Cal ifornia, Seismological Society of America, 1922. valleys adjacent to the east are outlined by faults. These faults run in,. a general direction , parallel to the Banner fault and the San Jacinto fault. Volcan mountain (5,570 feet) is extremely flat-topped and lies east , of Julian. b The existence of such a mountain east of the drainage divide and Banner fault points to a recent movement of t he Banner fault which has resulted in a disp_acement of two old land surfaces. Further evidence Plat1= rY, F.'~? substantiating this t heory is : (1) the existence of an antecedent stream/\ crossing the southern e:x:tension of Volcan mountain at Banner valley; (2} the difference in drainage pattern developed on both sides of Banner Canyon. East of Barmer Ca.."lJon on the slopes of Volcan mountain the streums are young, while west of Banner canyon the streams a.re mature. rhere is no difference i n the hardness of t he rocks on both sides of the 1 canyon. lO. Structure The major agencies that have determined the structure of the district a.re {l) compression, (2) igneous intrusion, and (3) faulting. A minor agent is that of landsliding. Compression has played an important ro1e in the development of the highly folded and contorted character of the schists and quartz veins. There have been three periods of compression. The first was before the intrusion, which developed the schistosity parallel to the bedding. The second accompanied the intrusion and caused a second schistosity to imposed upon the first. quartz veins. The third was subsequent to the formation of the This is exhibited by the folded quartz vein at the North Hubbard Mining Company and the crushed lenses of vein quartz caused by overthruat and reverse faults at the Golden Chariot Mine. I> The "Preliminary geologic map of San Diego County, California, r, 6 Ellis, A. J., U.S. G. S., Water Supply Paper 446, pl.3. shows one major fault zone passing through ~the district that extends from the southwest flank of Agua Tibia mountain along the southwest boundary of San Jose Del Valle, and passes th.rough Banner canyon. Hudson mentioned this fault in his report, but C,.id not plot it on his geological map, probably because of the lr...:k of sufficient evidence. At the head of Banner canyon on the new Julian-Banner road, which was built since Hudson studied the area, a zone of brecciation was observed approximately a hundred feet wide and a quarter of a mile along the fault. This, evidence along with physiographic evidence, proves that the Banner fault has been exceedingly active. E An approximate estimate 11. was made of the amount of vertical displacement effected by this fault. This was accomplished by finding the difference in elevation between the old erosion surface in the vicinity of Julian and the old erosion surface on Volcan Mountain. Correlation between these two surfaces was deemed advisable by the writer because of other physiographic evidence. The amount of displacement was found to be between 700 and 1300 feet. Ellis considers that a fault might also follow Chariot Canyon, swing east at Banner and continue north along the western edge of San Felipe Valley. A fault may exist along the edge of San Felipe Valley, but it is not present in Chariot Canyon for the reason that several quartz veins cross the supposed fault without offset. In the vicinity of the Blue Hill mine considerable landsliding has been effective so that the schists and veins now lie in a horizontal position. Parts of the vein have been displaced and scattered along the slope o~ the mountain about 200 yards from the original location. Geologic Hi story In regard to the age of the Julian schist series a number of writers have had ideas as to its age and the age of other schists existing in the Peninsular range. "1 Fairbanks, R . W., 7 Fairbanks correllated the metamorphics of Santa Ana Ce.lif. State Mi n. Rep. {XI), 18 93. with those in San Diego Co1U1ty . He found Carboniferous fossils in the Santa Ana region. 8 J.P. Smith concludes from fossil material found in limestone by 8 Smith, J. P., Middle Triassic Faunas of North America. U. s. G. s. Prof. 12. P. 141, 1927. Fairbaruts in the Santa Ana mountains, that the beds probably represent Upper-Middle Triassic age. C\ W, c. Mendenhall believes that the s1ates in the Santa Ana mountains in general resemble the Mariposa. slates of Central Ca lifornia. 1 Willis, Bailey, U, S. G, S. Prof. P., 71.; 10 Merrill regards the Julian schists as probably equivalent to the Calaveras group, described in the Mother Lode Folio of the United States Geological Survey, on the basis of structural position and lithologic characters. 10 Merrill, F. J. H., Geology and Mineral Resources of San Diego a.nd ., Imperial Counties, Calif. State Min. Bur., 1914, p. 12 . Hudson brings forth evidence, which is not entirely conclusive, "Op. cit., p. 190. of the finding of' an imprint of an ammoni to on an angu.la.r piece of quart zitic float from the schist series by D. D. Bailey of Julian, which was pronounced by Dr. J, P. Smith as Triassic. 'l1he age of the quartz diori te th.at int rudes the schist series is presumably pre-Cretaceous and post-Triassic and probably equivalent in age to the pihst-Mariposa granitic masses of the Sierra Nevada. rl'his is based upon the fact that in the S~ta Ana mo-i.mtains Cretaceous rocks rest upon the eroded surface of granitic masses of that general age. The Cuyamaca. basic intrusives, which are younger than the schists and quartz 13. diorite which they cut, are probably also pre-Cretaceous. From the above data t he probable geologic history of the region may be summari zed as follows: 1. Deposition of marine sediments during late Paleozoic e,nd Triassic 2. Uplifting and folding of the :.edi1,1ents before Cretaceous time. 3. During uplift a.nd folding of sediments, batholi thic intrusion time. of quartz diorite. 4. Intrusion of basic rocks followed by the formation of pegmatites, aplites, and gold-quartz veins. 5. Erosion of the region to low relief during most of Tertiary time. 6. A general uplif'.t of the erosional surface in l ate 'rert ia.ry or early Quaternary time, leaving the region substantially in the condition as seen today, except for minor eroslon. Economic Geology History of Mining:- Much of the early mining history contained in this paper was obtained by the writer from the State Mineralogist's reports and from Wu· . A. Frary, a pioneer of the early days when the gold properties were most actiYe. In the early days, prospectors were first attracted to this region by the discovery of placer gold at Wynola, three miles northwest of Julian. The first mines were discovered at Julian shortly after the placers were found. They were the Van Wirt and the George Washington. Both were located on the same day, Feb. 22, 1870. In August 1870, gold was discovered at the Redman mine near the mouth of Chariot canyon at 14. Banner by a Mr. Redman. • Relief by D. D. Bailey. This was followed by the discovery of the Ready The Golden Chariot mine located about three miles southeast of Banner was discovered in 1871 by a Mr. King. From 1870 to 1880 great activity prevailed in the district and the total production of gold was estimated at that time at $2,500,000. Ac- cording to a report made by the San Diego Chamber of Mines on the "Mines and Minerals of San Diego County," the total production up to the present time exclusive of the period between 1870 and 1880 , . ,has been approximately $7,500,000, which is probably much exaggerated. At the outset of the early operations a substantial zone of rich ore was taken out near the surface. amalgamation. The gold was readily amenable to As the mines appraoched water level, the sulphide content of' the ore increased, the gold values decreased, and, due to the hardness of the rock combined with the added cost of pumping, mining became much less profitable. With an increase in sulphides int::.~ or::i, amalgamation became impractical so that r·oasting of the ore was resorted to with little or no success. ' Assays are rarely run on the ore by the prospectors. The grade of' the ore is determined by grinding it in a mortar, washing the material in a miner's pan, and then noting the length of the string of colors. At present the camp is very quiet, though many owners are keeping up assessment work in hope that financial conditions may change and that mining properties may again become saleable. Within recent years, since 1922, the Golden Chariot, Ready Relief, and Hubbard Mines have been worked intermittently. Gold Quartz Veins:- There are four main veins in the reglon with several adjacent parallel veins, all conforming to the dip and strike of 15. the schist. The main veins are in some localities accompanied by smaller parallel veins or stringers of no importance. The general strike of the veins is northwest and the dip is either to the northeast or southwest. Where landsliding has been effective, the dips are considerably flatter. Where possible, the writer has ad.opted the name of the vein in current use, otherwise he has taken the name of the first mine located on the vein. The first vein, {see fig. 2) going from east to west is the Chariot vein, which is knov;n also as the Contact vein. Followed by this in consecutive order are the Ready Relief, High Peak, and the Van Wirt veins. One mile southeast of Banner is located the Ranchita vein in an isolated schist mass surrounded by quartz diorite. The width of the gold quartz veins usually varies from a few inches to two or three feet. In one locality, about one third of a mile south of Banner where t wo veins come together, a width of about fifty feet is s.ttained. '1.1he structure of the veins in the district is exceedingly interesting because var:ous areas have had. different structural histories. The major factors controlling these various structures are compression a.nd faulting. At the Golden Chariot Mine, (see fig. 5.) cr4shed lenses of quartz predominate. This has been due to post~ineral overthru.st faulting. Movement along the vein has been very pronounced and for the most part the vein, together with a certain amount of ct u.shed country rock, lies between smooth walls. In certain places these walls leave the lode and pass as slips into the country rock, diverging at small angles to the dip and strike of the vein. At such_ places the lode for a short distance is without a well-defined footwall or hanging wall. It appears that the 16. stress which produced the slickensided walls was exerted in directions that, in homogeneous ma:teria.l, would have resulted in fissures oblique to the vein. The angle of obliquity was foui1d to be about fifteen deg- reas in most cases, a lthough where the angle was smaller the movement took place along the vein. 'f:he grooving and slickensiding noted in some places on the walls of the vein indicate that the last movement was horizontal instead of vertical. To the east of the Cha.riot vein on the Ready Relief vein at the Ready Helief and Hubbard mines, the vein has been folded (see fig. 6). This folded character can be seen in a few of the mines on the same vein to the north. .rh.e vein takes the form of a succession of "rolls," de- 1 scending toward the hanging wall at a somewhat less angle to the northeast than the schist. The dip of the schist is 70 to 80 degrees to the northeast while the vein is somewhat flatter. As far as has been observed the schists are not folded to correspond with the vein, but simply ·bend around the kidney-shaped rolls or abut against them. The 4u.artz cleaves away from the schist leaving smooth concave or convex surfaces. No gouge separates the q_1;.artz from these surfaces. A number of hypotheses have been advanced regarding the origin of the "rolls, Tt I '1. In referring to these "rolls," Hanks says: 1'2. Hanks, H. G. Sixth Ann . Rep. Calif. State I.fin. Bur. pp. 87, 1836. "The vein is interstratified wHh the clay slate formation. The slaty cleavage of the country 1.·ock is undoubtedly clue to lateral pressure, which has also distorted and plicated the veins, so that it is found in folds, which are teclu1ic a lly called 'rolls'. I am inclined to the opinion that the vein was formed by solfataric action in plastic mud 17. before the mountains were elevated and that the vein has been plicated by its own weight while still in soft condition." This theory does not take into consideration that the other veins in the district could not have been formed under the same physical conditions. 1 Fairbanks J10tes, as does Hudson, that the schists have a double 1\-airbanks, H. W., A Remakkable Folded Vein in the Ready Relief Mine, Eng. Min. Jour., vol. 57, pp. 321-322, 1894. scl1istosity. He infers from t his that when the second schiatosity was imposed upon the schists, zigzag fissures were developed across the strata, the course being determined by the competence of the beds. Fol- lowing this the fissU!'e would continue in the cleavage for a short distance, and then a.gain repeat the process. The siliceous waters circul- ating through this at first jagged fissur e , gradually absorbed the roughness of the walls as the deposit of silica kept growing, thus leaving a greater deposit parallel to the slaty cleavage until there resulted the :.smooth rounded rolls. In examining s2.mplea of the vein quartz under the microscope, the individual quartz grains exhibited s train sh1-1dows while the mass as a whol e showed a cataclast ic texture. . ated parallel to the schistosi ty. The quartz gr ains have been elongThis proves wi thout doubt that the folding of the vein has been post-mineral instead of pre-mineral as advocated by Fairbanks. In most of the mines in the district the quartz veins occur in lenticular masses that have not suffered deformation such as is exhibited 18. by the quartz lenses at the Golden Chariot Mine. the lenses of quartz are arranged en echelon. In several of the mines The size of the lenses vs,ries frorr.. a few feet to several thou.sand feet in length. The development of lenticular ore bodies by shearing subsequent to 14 ore deposition has been discussed b;y Graton. At the Golden Chariot mine 1~G ra t on, L. 0.., . , Go-1 d and '-l 'ln · Depos i ts of the Southern Appalachians, TTv. S. G. S. Bull. 293, pp. 35-37. 1906. post-ore metamorphism certainly has played a l arge .: part in causing an en echelon arrangement, but ·this can not be applied to some of the mines in the district because the laminations of the schist d.oes not curve around the end of the lenses, but the quartz lenses die out in a series of parallel stringers. Presumably the en echelon arrangement was determined b;y· zones of less competent beds before a second schistosity was imposed to deform them. The vein-like extension would represent deposition in more com16' petent beds according to Hanson. 15 Hanson, G., Pyritic Deposits in Nietamorphic Rocks, Econ. Geol., vol. 15, p. 606, 1920. General Character:- The gold-q_uartz veins a.re either lenticular, f olded, or continuous fissure fillings. As a rule t he banded q_ue.r tz, which usually carries the highest gold valu.e1, , is -· confined to the l enticular masses. These have been formed. in large part by post-mineral meta.morphism. At the Shamrock mine where the vein is fairly conti.nuous, the banded quartz carries no gold. • At the Golden Chariot mine the banded quartz 19. (see plate I, fig. 1), which carries gold, is characterized by having a ribbon or sheeted structure. It occurs either in lenses or in a fairly continuous vein of as much as fifty feet in length. 'l'his type of struct- ure ha s presu.~ably been formed by repeated filling of small openings l~ produced by interminera.lization fa.ult movements. lb Hulin, c. D., Structural Control of Ore Deposition, Econ. Geol., vol. 24, pp. 15~50, 1929. Mineralogy Ore Minerals Native Gold: '.Phe gold i n the q_ua.rtz veins contains variable a.mounts of silver and is always of a lighter color if considerable silver is present . Coarse gold in the form of nuggets was taken out of t he mines near the surface in the early day s . Some of the gold occurs in thin sheets in the sheeted zones and as threads and microscopic particles distributed throughout tne quartz veins. The gold in the oxidized portions of the veins was probably derived from auriferoua arsenopyrite and pyrrhotite. Arsenopyrite: '11his mineral occurs ma inly in small stringers in ·the quartz veins, where it is found in massive, granular, or crystalline forms. In some of the mines, especially in the Golden Chariot, the gold • is closely associated with it. Pyrrhotite: quartz veins. Found as stringers or laminae near t he mar.gins of the Botl,• t he cryst~lline and massive forms occur. When sub- jected to weathering, the pyrrhotite becomes tarni shed to the colors of red and blue so that it has the appearance of bornite. Relief and Hubbard mines it is associated with gold. At the Ready Washington High Peak Ready Relief Chariot Vein Vein Vein Vein Pyrite X X X X Arsehopyrite X X Pyrrhotite X X Minerals Molybdenite Albite X X X X X X X Table Showing Distribution of T!iinerals Fig. 3. X 20. Pyrite: r.rhis mineral was found to be confined mainly to the mar- gins of the quartz veins. mon. :Both the lamellar and granular forms are com- In no place did the writer observe pyr ite associated with gold. Molybdenite; scales. Segregated masses in the quartz occur in the form of It is associated with both pyrite and pyrrhotite at the Hubbard mine, the only locality known to the writer to contain molybdenite. Gangue Minerals Quartz: Color white to greyish-white with a coarse massive texture. The structure is hypidiomorphic and under the microscope the quartz shows in some specimens a cataclastic texture with strain shadows in the individual grains. "Sugar" quartz is found at the Golden Chariot mine. The formation of this type or quartz has been due to post-mineral faulting which ha s crushed the ori g.irw.l coarsely crystalline quartz vein. Albite: This is found associated iu small amounts with quartz al- though in some localities a lbite predominates over the quartz, giving the vein a pegmatitic aspect. Kaolinite: This mineral occurs as an alteration product of albite and probably sericite. Sericite: wall-rock. It is found in the zone of oxidation. A common constituent of both the quartz vein and schist It is an alteration product of the wall-rock. Gra.phitic material occurs on the wall-rock of the veins in both the Heady Relief and Golden Chariot mines. It is due :presumably to faulting and squeezing of the schists as numerous slickensided surfaces are developed on it. Paragenesis:- In studying the order of crystallization of the min- ,... Minerals lst Generation. 2nd Generation Alb'ite Pyrrhotae Gold L ..J 21. erals contained in the gold quartz veins, the writer was handicapped by the lack of a complete suite of sulphide samples,· because many of the mines are still above the water level. A study of the polished sect i ons of the ore brings out certain pertinent facts present themselves. (see fig. 4.) The normal order of cryst- allization was found to conform with the paragenesis of me sothermal und 17 hypothermal gold-quartz veins summarized by Buschendorf. Where molybden- \£ Buschendorf, F., Zeitsch. Prakt. Geol ., 1926, pp. 1-11. ~1, ',i ite occurs in the crystallizing sequence of the eulphides, the writer could not exactly ascertain. From a ll indications it appeared to have crystallized out later than the pyrite or :pyrrhotite, which is contrary I~ to its usual order of deposition. li Cissarz, A., Heuen According to Cissarz it is a pneumat- Jahrbuch fur Hineralogi, Beilageband 56. Abt. A., 1927, p. 136 . olitic mineral which has crystallized out before or contemporaneous with the quartz and albite. Genesis;- The deposition of the gold-quart z veins without much doub·t followed t he intrusion of the q_u.artz diorite ancl i s closely assoc- " iated with it. '11he veins are presumably a transition between meoothermal J9 and hypothermal gold-quartz veins, because of t he pre sence of molybdenite 19 Lindgren, W., Mineral Deposits, p . 746, 1928 . and pyrrhotite which are usually rare minerals in mesothermal deposits. No high temperature minerals were found, such as apatite, tourmaline, magnetite, and garnet. 22. The writer was not able to trace t he pegrna.tites dikes into q_uartz veins directly. At one locality, however, the Chariot vei n , between two Quartz vein outcrops, t he writer observed a pegmatite di ke made up of orthoclase, albite, and quartz separated by bands of pure quartz, which would probably indicate that the pegrnati tes mi ght form a tra.nsiI tion between the magma a.11d the gold-quartz veins . The gold., which is lar gely later than the a.rseri.opyri te, is found also to have been deposited contempora.neouikly. t. It has been shovm by 'l.0 Palmer and Bas}n that a.rsenopyrite is an extremely effective preci pitant '},.0 Econ. Geol., vol. 7. pp. 140-170, 1913. of gold. This would indicate that arsenopyrite, to a great extent, det- ermined the ore shoots. The localizat i on of rich ore shoots especi a lly above the water table . would indicate that some enrichment may also have taken place by 1.he re'.l. \• mova.l of valueless material, as sugges ted b;y Ri ckard. No porou.s, cellular "l. \ Ri ckard, T. A., '1.1l-1e Formation of Bonanzas in the Upper Portions of Gold Veins, Am. Inst. Mi n. Eng ., Trans., vol., 31, pp. 198-220, 1902. ·o re containing much limo~i te or hematite was observed, so that it is dif. ,.. •.,. . . .. , . ,• , ~- ficult to determine the a.mount of pDee-epace left by the removal of sul;l1ides by solutions. Placers:- Al t hough the q_uartz veins show free gold. at the surface, placers are not common. Placers, however, have been worked in a small way at Coleman Creek and near Wynol a. . Colors can be obtained from either Banner or Chariot can;yons, especially where Banner creek joins the Char- 23. iot Creek at Banner valley. Conclusions and Practical Deductions 1. There are four !Jain parallel gold q_uartz veins in the schist series which conform to the strike and dip of the schis t. 2. The order of crystallizati on of miner a l s follows the usual or- der of deposit i on of pyrite, pyrrhotite, molybd.enite, arsenopyrite, and. gold. 3. Veins occur in three forms : a. "Rolls." b. Lenses which are in en echel on arr angement . · c. Fissur es . 4. "Rolls" have been formed by post-miner al metamorphism. 5. En echeloJ'l arrangement of t he lenses have been due in pa.rt to :pre-mineral compression parallel to the strike of the schists, causing e lliptical openings in less competent bods and straight fissures in mor e competent beds. 6. After the forma.t fon of the elliptical openings and s traight fissures, these were filled b y mineralizing solutions. 7. l'ost-mineral compress i on normal to the strike of the schist has ca.used in part the for mat ~on of lenses of vein quartz. 8. The Juli en veins are intermediate in character between the Moth- er Lode mesothermal gold veins and ~he Appalachi an hypothermal gold veins. 9. IJ.1here is some indicat ion that the pegmati tes may grade into quartz veins. 10. Previously deposited arsenopyrite and pyrrhotite probably deter- 24. ed the position of t he ore shoots. Tho stu.dy of this district has l ed t he writer to mak.e certain deductions which may httve u practical bearing on futru·e operations. Some gold is f ound al ong the entire lengt h of the quar tz veins, but ~mly ceri;ain portions of the veins are rich enough to mine. 'I 'hese richer portions ru:e as a general rule conf lned to the narrower parts of the vein, which necessitate s the 1·em()ve.l of a large amount of waste rock in extracti ng the ore, thus bringing t he tenor of the ore down so low that it makes it unprofitable to work at times. A good grade of milling ore may be expected. a t de pth because this type of vein us;ia,lly persists with depth. The wri ter believea that only a small amount of enrichment has taken place in these veins a'bove the wa ter table. lt is res.sonable to assume the.t the ore shoots carry gold below t he wa;te:.· t able, but a decided change in the character of ere has ta,ken place at wat er level. The change from oxidiz ed vein materb.l car- r;ylng free gold whi ch is !il!lenaole to amal garr!ation, to go ld associated. with arsenopyrite, pyrrhotite, and pyri te * will necessitate a change 3.n the metallurgy of the ore. l11he chief factor that caused some of t he mines to close down when they had reached water level was the increased sulphide content of t he ore. On,Ja continuous vein running f rom Julian to Banner t1'..roUt,-m a. vert i cal r ange of 1500 feet, gold is found throue.)'lou.t ~i;s entire lengt h . Julian. The vein is a s rich in gold content at Hanner as at This criterion substantiates the possibility of gol:i being fou..YJ.d at depth. r:_ _ _---,., Quartz. 5ch,st Gneiss Quartz D1orite 5tlct1on of Ouarz Lens«.s ..J ' " ' Level •)t/1 ,--~ Gros.s e..t,---1 ooJ or-.., \,IJnzG \,,l'inze [ ;r· ... -It" ! ..., ,-, t•·,. ...... bin -I<' Gross e<l't ,?' Kl 300' Leve.I a: .a 4) tt ~ ioo - ~ :,oo pu ton Raise C,_ cut C,.-ou e..AT :-1 cut 67' W' 1.- l-\ H Good o,...e; -<'I" - \ 7 F~.7 Cros!> c.uT r1 -- • tl: "'I) '\) ... -; ~ . _£ V) lo, 5urnp Sca\e Gro..s~ 1••:::. op1'.lr,/'.?,c,70 \ ______,,_·...•-~ 1es' )..eve LI • -- Cro•~ c..ut E. D l I Lo~1tud,nal Section of Chariot Mlne Z. 50 'Leve □ * .It 19t3 Stopc.o ~ ++ ,i , 25. Mines Golden Chariot:- 'l'his mine is owned b:; the Golden Chariot Mining Corporation and consists of two 9atented claims; the Golden Chariot and the Chariot North, and four ~.n.patented claims. The property is located three miles southeast of Banner and was ori ginally discovered in 1871 by:: a l'x . King. It was later ta.ken over by Mr. James Mc Donald abou.t, ·, 1873 who organized the Char iot Mill and Mining Company and o·btained. a United States patent for the gr·oQnd. Upon the death of M:r. Mc Donald the property closed down and was not reopened until Nov. 1922, when Mr. C. A. Ferrin was given a lease and an option on the mine. The total production of the nine has been ~J,1,800,000. The mine is located on the Chariot or Contact vein between a . q_uartz diorite hanging wall and a schist footwall. ( see fig. 5~ and 7) Schists dip about 70 degrees northeast. and strike N. 10 degrees W. '11he schists that have b,,en subjected to weathering have the appearance of sl ates. The q_ua.rtz vein in the mine occurs either as lenses (see Plate L fig 2.), stringers, or as straight continuous fissure fillings for distances up to fifty feet. There ha s been a large a.mount of compres- sion and sh.ea.ring as exhibited by crushed and brecciated. character of the ~uartz and ~all rock. This has been due to post-mineral overthrust faulting. The ore shoots usually occur in lent'1cular masses of quartz and the richest ore is found in the banded quartz with a sheeted structure. North Hubbard Mining Company:- This company owns the Nor-th Hubbarg,, Ready Relief, Redm~ and Hidden Treasure 1.lines. The Ready Relief mine has produced $750,000 while the North Hubbard has produced about $250,000 r ,-----_ _., I ~j + ~\ I '\ \ I\\ SECTION OF Fo ~oto L.. \ E.t N .J 26. in gold. The Reacly Relief mine, which has been the big producer, was first located in 1871 by Mr. D. D. Bailey, who worked the property for a long time. In recent years the property has been worked by a nwnber of lessees. The main workings can be reached either l?Y an adit or by a. shaft which is 200 feet deep. These workings are in a fine- grained fissile mica schist which has the appearance of being slate. The workings at the Hubba.rd mine are reached by an adit 248 feet long and are in t he same type of rock as the that found in the Ready Relief mine. The schists in both mines dip about 70 degrees northeast and strike varies from N. 15 degrees VT. to N. 40 degrees 1!/ . An interesting feature r;g,b about these mines is the folded veinAwith large amounts of pyrrhotite accompanied by a small amount of molybcleni te anc1 no arsenopyr l te. A con- siderable runolL~t of alum is f ound as an alterat Lon 9roduct of the schist, which has been formed by the reaction between iron sulphate and the schist. PLAl'E Fig. 1. :Banded gold-vein I. quartz from 300 foot level of tne Golden Chariot mine. Fig. 2. Specimen of a gold-quartz vein lense from 300 foot level of the Golden Cha.riot :Mine. ..J PLATE Fig. 1. II Polished sect ion of ore from the Itea.dy Reli ef mine, show- ing pyri t e surrounded by pyrrhoti te . x 200. py, Pyrite; pr, Pyrrhotite; q, Quartz. Fig. 2. Polished section of ore from 165 foot level of the Golden Chariot mine, showing that the gold is contemporaneous with the arsenopyrite. x 200. as, Arsenopyrite; g, Gold. PLATE Fig. 1. Polished section showing the gold veinlets cutting the arsenopyrite. Fig. 2. Ill x 200. as, Arsenopyrite; g, Gold; q, Quartz. Polished section showing gold cutting the quartz. g, Gold; q, Quarts. x 200. PLATE IV Fig. 1. Looking northwest along Banner Fault. Fig. 2. Looking due east at Banner valley in the foreground, at San Felipe valley and Granite mountain in the background. The stream running from Banner valley into San Felipe valley across the southern extension of Volca.n mountain is presumably an antecedent stream. , li'5. g . l . Looki ng d 1e s ou.t h d Fig . 2 . Ad.it of t Le Hea.d.y Itelief mine . gol d- qUb.r t l. vein . Go llhm Ch ari ot 1::::. :w . Line indi c a t es .L i.ne :., i1;.di c £..t e o: : i tion of ., I., .,, 0-o ..J /\ I 7J J)) r+- ro ? LA'l1:S I!'ig . l. Fh otomi cr ogr a1-1h of t h i n s e c t.:. on s h owing br e ccia t e d char-· a c t er of the ve in qua rt z 1;,,t Fi g . 2 . VI the heud.;y r: e l i ef mi ne . PL ot rn1icrogra.ph o f t h l 1t S ('.j C t i or '. s}cowi ng bre ccia t e d cha r - 1;, c ter of t he vei.n qi.:..ar t z a t tL e Golden Clmri ot mi n e . ?LATE Fi g . l . VII l.li l l c.t t J-ie Heu.dy l ,e l i E: l' a,i w2 wh ici:1 .is o i tu.a t e<.!. near· t ha uouth of Char : ot canyon . 1' i g . 2 . Lo ok i ng nor t hwe s t a lon g t :,s ve i n s ar.d c o!1 tac t between s chis t a nd qt:a rtz dior it e . .,