short a time during the year that the miners were only temporarily located in the vicinity of their mines; as a rule, they were permanent residents during the year, so that the total of 302,860 men employed may be taken, with their families, to represent the permanent population around about the coal-mines of the United States.

In the second place, the number of miners employed depends upon local conditions peculiar to each mining district. Some of these conditions are the thickness of the coal-bed, the hardness or softness of the coal, the existence or absence of thin layers of slate or clay included within the body of the bed, which necessarily retards the mining, the care which is necessary to remove the slate and bony coal from the market product, and the necessary handling of the coal between the mine-mouth and the railroad shipping car. Much also depends on whether the coal-bed is comparatively horizontal, or dips at various angles, owing to an irregular and complex geological structure; whether the bed is mined from self-draining drifts and tunnels, or from the bottom of slopes and shafts, from which the coal has to be hauled and the mine-water pumped; whether the coal has to undergo any preparation after it is taken from the mine, before it is in condition to ship to market; whether it has to be washed, as some of the Pennsylvania anthracites and Southern bituminous coals have to be; whether it has to be broken down in commercial sizes, as is the case with all anthracites. Many other conditions might be named which directly influence, though to a small degree, the number of laborers which are required for the mining of a definite quantity of coal.

Taking 10,000 tons of coal mined per year as a unit of product, I find that the number of inside and outside laborers taken together, which are employed about the mines, varies from 17 as a minimum in the State of Maryland, to 26 as a maximum in the State of California. In West Virginia the number is 18, in the Pennsylvania bituminous region 19, in Kansas and Indian Territory 20, in Illinois 21, and in the Pennsylvania anthracite region 23. In all the other States and Territories in which coal is produced, the number of men employed for the production of 10,000 tons of coal per annum varies from 22 to 25. The peculiarities in the character of the coal-bed, which have already been referred to, influence not only the number of miners employed in mining a unit of product, but the rate of wages paid, it being obviously just that where one miner can mine twice as much coal in one district as another equally competent miner can mine in another district, that there should be a

marked discrimination in the amount of wages paid to each. While it is of great interest to coal operators and to the mining laborer to be informed as to the rate of wages paid in different districts, yet, unless the local conditions peculiar to each district are fully understood, no just appreciation can be formed as to the absolute daily profit realized by labor in each locality.

In addition to the conditions which affect this question already noted, it is important to bear in mind the different purchasing value of a dollar in the different mining communities, in any estimates made of the actual earnings of the miners and other laborers in and about the coal mines.

THE ORE-DEPOSITS OF RED MOUNTAIN, OURAY
COUNTY, COLORADO.

BY T. E. SCHWARZ, RED MOUNTAIN, COLO.

(Colorado Meeting, June, 1889.)

THE Red Mountain district, in Ouray County, Colorado, has been already referred to in the Transactions of the Institute, and notably in papers by Mr. T. B. Comstock, on "The Geology and VeinStructure of Southwestern Colorado" (Trans., xv., 218), and on "Hot-Spring Formations in Red Mountain District, Colorado-A Reply to the Criticisms of Mr. Emmons" (Trans., xvii., 261), and in the paper of Mr. S. F. Emmons, on "Structural Relations of Ore-Deposits" (Trans., xvi., 804).

The district has attracted much attention from those interested in geology, because it seems to present a variety of ore-deposits rarely, if ever, met with elsewhere, and one which cannot be described by such well-understood terms as fissure-veins, bedded-deposits, or con

tact-formation.

It will be the scope of this paper to note briefly, from the writer's experience in developing the Yankee Girl, Guston and other Red Mountain properties,-first, observed facts as to the ore occurrence and formation, and second, certain unsolved geological questions.

The Red Mountain district proper occupies the headwaters of Red creek, from Ironton to the Divide, a distance of 5 miles. Its leading properties occur on the west slope of Red Mountain. The mode

of occurrence of the ore of Red Mountain, in its entire extent from Ironton to Silverton, 10 miles distant, is, however, identical with that of the limited district to which this paper refers. Outside of this district the development is slight. Its mean elevation is about 10,800 feet above sea-level, while the adjoining peaks rise to about 13,000 feet. It is in the heart of a very extensive area of eruptive rocks, andesites, trachytes, and breccias, in which occur the most productive camps of the San Juan country, such as Marshall Basin, Mt. Sneffles, Mineral Point, Lake City, and Silverton, all within a radius of 15 to 20 miles.

The topography of the district itself is characteristic, and indicates something of its past history. It is marked by bare, ragged cliffs, and red patches of oxidized material on the upper mountain sides, while below are considerable areas of heavy slide-rock, carrying large detached masses. Between these areas of detritus occur benches and terraces covered with shallow soil, and diversified here and there by knolls or mounds of hard, porous, siliceous rocks, with a reddish hue or stain. They sometimes rise above the surrounding bench in a broken cliff, with a sloping base of rock fragments; or again, barely show an outcropping of quartz. The basin presents a very rough, broken surface, showing every where the effects of heavy erosion, and of an active period of metamorphic action. Good water is not to be found. Iron springs abound, and, in depth, the mine-water becomes all that is objectionable, carrying 24 grains of SO, to 1 U. S. gallon, and readily disposing of a 4-inch thick wroughtiron column-pipe in four weeks' time.

The ores of the district may be divided into two groups, viz.:
A. The secondary, or oxidized ores.

B. The primary, or unoxidized ores.

In some properties ores of both characters occur, the one beginning where the other terminates.

THE SECONDARY ORES.

The secondary ores occur above a former water-line, either attached to the walls of caves, as broken, detached masses, or as a bed of clayey mud or sand, more or less completely filling the caves. The cave formation is identified with the massive outcroppings or knolls of silicified andesite, ordinarily termed "quartz." These knolls rise from 25 to 200 feet above the surrounding surface, and while sometimes quite conical in appearance, they more generally have a greater length than width, in some instances being 400 to

500 feet long, by 200 feet wide. They present a rough mass of quartz, cut up by cross fractures, and showing small vugs and cavities on the exposed cliff-faces. The ore-bearing caves, which ramify throughout the mass, generally come to the surface along the cliff-base, where they are partially or wholly covered by slide. In size the caves vary up to chambers of 50 feet in diameter, which are connected by irregular rounded passages, branching out towards the surface, but diminishing and coming together in depth. The ores are mainly carbonates of lead and of iron, together with the iron oxides, lead sulphates, and arsenates. Kaolinite occurs in considerable quantities, and zinc-blende is common. The latter occurs in botryoidal masses, consisting of nearly concentric fibrous layers, and is usually found detached from cave-walls. Galena also occurs, but generally as the core of an oxidized mass. Such are the ores of the National Belle, Grand Prize, and Vanderbilt mines, while other properties near by, viz., those in the Enterprise group, omit the lead minerals and carry the oxide and sulphide of bismuth. From these latter ores, sorted to a grade of 25 to 50 per cent. of metallic bismuth, several hundred pounds of the metal have been reduced by Messrs. Mentzell & Kellar, of Durango.

The following are the prominent features of the secondary ores: 1. The secondary ores are richer than the sulphide ores occurring below them.

2. The ores of adjoining or connecting caves are sometimes greatly different in grade.

3. In some cases the formation of the caves along fracture or cleavage planes is evident, but in others all traces of such planes are quite obliterated.

4. The cave-walls are a porous, sandy quartz, the sand from the disintegration of which forms part of the cave-filling.

5. The line of change from oxidized to unoxidized ores, or the former water-level, is very marked. It varies as much as 100 feet in elevation in properties within 1000 feet of each other, rising to the south and west. The quartz outcrop rarely rises more than 200 feet above it.

6. In isolated cases may be found masses of the unoxidized ore, the enargite, above the line of change, in the vicinity of the secondary ores.

The formation of these ores is readily accounted for in the oxidizing and dissolving properties of surface-waters, which, moving along fracture planes, took into solution the original sulphide-ores and