This interesting region has come quite prominently into public notice within the past two years. The district is located in a small range of mountains about 35 miles east of the Calico range. The nearest station to the mines is Lavic, on the line of the A. & P. R. R., from which point the mines are 9 miles distant by a good wagon road. Like most other desert mining regions it is destitute of timber, and water is not abundant, though obtainable in the dry lake basin 3½ miles from the mines. The district was discovered about nine years since, and numerous claims have been located. The work of development has been confined to a few of the most promising claims. GENERAL GEOLOGY. The mountain range in which the mines of this district occur is isolated from all others, although evidently a part of a chain extending in a northwest and southeast direction for many miles. This particular group of hills is about 4 miles in length by 1½ in width, and consists of rocks, which are all of plutonic origin. They are mostly quartz porphyry of the normal type, consisting of a fine-grained felsitic ground mass, with macroscopical crystals of quartz and feldspar. Of several thin sections made for the purpose of microscopic study of these rocks, their behavior under the microscope is so similar that general description will suffice for all. The section is characterized by a micro-crystalline to micro-granular ground mass, sometimes to globulitic. The feldspars are so completely clouded as to leave little clue to their identity. Some still show faintly the parallel lines which are so characteristic of plagioclase, but some of these feldspars are probably orthoclase. These feldspars are plainly distinguishable in the rock mass with the unaided eye. Quartz blebs as large as small peas, with many smaller ones, occur plentifully in all of these rocks. In the section they seem to have been corroded, the outlines being nearly always rounded, though frequently showing hexagonal forms. Most of these quartz grains polarize in brilliant colors. All of the quartzes contain a great abundance of fluid inclusions, some of which show included air bubbles. Numerous very small, colorless, needle-like crystals, which occur in all the quartz, are no doubt apatite prisms. Green, dust-like hornblende as inclusions are not at all uncommon, and in one section a mass of green, fibrous material, having all the optical properties of hornblende, is seen. This inclusion is large enough to be easily distinguished with the unaided eye. There are numerous globulitic, granular, and sac-like inclusions of the ground mass in many of the quartzes, which is characteristic of the quartz porphyries generally. Besides these macroscopic crystals of quartz and feldspar are many hornblendes, some of which are of good size, a few having the typical crystal outlines. It is usually of a bright green color, strongly dichroic, and polarizes in the usual colors.