This paper describing the methods of concentrating tungsten ores at the mills of the Atolia Mining Co. is one of a series of similar papers being prepared by the United States Bureau of Mines. The writer acknowledges the assistance and cooperation of A.V. Udell, president, Louis Warnken, bookkeeper, and C.K. Dennis, superintendent, of the Atolia Mining Co. in the paration of this paper. The Atolia district is in the western part of San Bernardino County near its boundary with Kern County, Calif. The district lies in the northern part of the mOhave desert, 40 miles east of the town of Mohave and 23 miles north of Kramer. The latter is a station on the Atchison, Topeka and Santa Fe Railroad and it is the southern terminus of a branch line to Johannesburg via Atolia. Train service over the branch railroad at present is operated on a daily schedule.