Escabrosa limestone. Most of this ore has come from the Southwest mine and occurs at the edge of the siliceous breccia, as cerussite with some

FIG. 2.-CHALCOCITE AND MALACHITE. ALTERATION RESEMBLING INTERGROWTH.

PLATE 17.

anglesite and variable silver and gold values. The primary minerals from which this ore was derived are unfortunately not present now, but

it is very probable that the main one was galena, which, as has been before stated, is apt to come in vein-like masses above the general level of the copper ores. Lead ores have also been found with similar associations in the Gardner, Lowell and Briggs mines.

Vanadium, in the form of cuprodescloizite has been found in the Shattuck mine in considerable amount, and rarely in the Dallas and Sacramento. The occurrence may prove in future to be of economic importance.

Manganese ore, in the form of psilomelane and braunite, with little pyrolusite, has been mined lately from several places on the surface of the district. It is found in irregular bunches as a replacement of limestone beds in the Naco or Escabrosa, close to the contact breccia, or to highly silicified outcrops of the sediments. The origin of this manganese is not yet known, for although manganese is found quite abundantly with some of the carbonate ores underground, it is here in the form of soft earthy pyrolussite due apparently to the concentrating action of oxidizing water.

BIBLIOGRAPHY

The most important published works on the geology of the Warren district are the following:

JAMES DOUGLAS: The Copper Queen Mine. Transactions, vol. 29, pp. 511-546 (1900). FREDERICK L. RANSOME: Geology and Ore Deposits of the Bisbee Quadrangle. U. S. Geological Survey Professional Paper No. 21 (1904).

Bisbee Folio, U. S. Geological Survey, No. 112 (1904).

ARTHUR NOTMAN: The Copper Queen Mines and Works, Part II. Transactions of the Institution of Mining & Metallurgy, vol. 22, pp. 550-562 (1913). W. L. TOVOTE: Bisbee, a Geological Sketch. Mining & Scientific Press, vol. 102, pp. 203-208 (February, 1911).

Mention must also be made of the report on the mining geology of the Copper Queen property by John Mason Boutwell prepared in 1908-1909 for the use of the mines, one of the results of this work being the establishment of the present Geological Department.

ACKNOWLEDGMENTS

To the Copper Queen Consolidated Mining Co. for its support and encouragement in the preparation of this report, the greatest thanks are

due.

Arthur Notman, Chief Geologist of the Company, has lent the utmost assistance, contributing from his store of knowledge gained by long and careful investigation in the district and in this part of the Southwest as a whole.

Former members of the Geological Department, and our colleagues of the Calumet & Arizona Mining Co., have also contributed materially to the information presented.

To Harvard University, and Prof. L. C. Graton in particular, we are indebted for being able to present the result of extensive petrographic and metallographic investigation, as 2,000 specimens from the Copper Queen geological collection were studied by one of the authors in the geological laboratories at Cambridge. Some of the photomicrographs were taken at the University of Arizona, for which thanks are especially due to Prof. C. H. Clapp.

Assistance has been received from the engineering department of the company in the way of maps and stope records, and from the chemical department in the form of the analyses that are given in the report. Thanks are due to the operating department of the mines for a great deal of information, also for coöperation in pointing out and solving most of the geological problems of the district.