Miscellaneous hematite deposits.-Hematite occurs in small scattered deposits of various forms, such as veins, breccia deposits, and replacements in many of the Western States. These deposits have not been sufficiently studied to be definitely classified. The following are some of the principal localities:

In the Cebolla district, Gunnison County, Colo., hematite and magnetite occur in limestone as layers and veinlike bodies conforming to the bedding of the inclosing rock. The deposits vary up to 10 feet in thickness. Associated with the hematite and magnetite are iron carbonate and limonite, which grade directly into limestone, the limonite being an alteration product of the iron carbonate. Locally considerable manganese ore is associated with the iron ores. Small veins of hematite occur in granite north of Cotopaxi, Fremont County, Colo. The largest of the veins has a maximum width of 3 feet and a length of 80 feet.

Similar deposits of hematite occur in granite a few miles northwest of Livermore, Larimer County, Colo. They are small and unimportant.

A deposit of specular hematite a few feet in thickness occurs on the Atlantic Cable claim near Rico, Dolores County, Colo.

A body of hematite the size of which is not known occurs in crystalline schist in Cochetopa Creek south of Parlin, Gunnison County, Colo.

Near Elizabethtown, Colfax County, N. Mex., there is a vein of specular hematite 5 to 7 feet in thickness. Other hematite deposits are found in New Mexico in the Capitan Mountains and in the Jarilla Mountains, but they are of no importance.

A deposit of hematite of brecciated character occurs in Rhodes Plateau, in the western part of the Uinta Mountains, Utah. The ore is in lower Carboniferous limestone, which it replaces along lines of fracture and brecciation. Unimportant bodies of hematite are reported from Cave Creek, north of the Mineral Range, Beaver County, and from Bear Valley, in the western part of Iron County.

An important body of hematite in pre-Cambrian metamorphic rocks occurs at Planet, Yuma County, Ariz., but the relations of the ore are not known to the writer.

South of Seligman, Yavapai County, Ariz., there is a large deposit of high-grade hematite in limestone. The outcrop is reported to be 600 to 700 feet long and 10 to 20 feet wide.

Small unimportant deposits of hematite are scattered through the Sierra Nevada and Coast Range in California. Such ores have been reported from Meadow Valley, Plumas County; from the southwestern part of Nevada County; from Ione and Clinton, Amador County; from the western part of Sonoma County; and from San Diego County.

Several deposits of hematite are found about 14 miles west of Valley, Stevens County, Wash. They are associated with limestones, slates, and schistose rocks.

BROWN ORE.

Limonite gossan ore.-A gossan of limonite occurs in many localities in the West as a capping of metalliferous sulphide deposits. Probably the most important localities where these occur are the Black

Hills, S. Dak.; Neihart and Monarch, Cascade County, Castle, Meagher County, and Elkhorn, Jefferson County, Mont.; Leadville, Lake County, Colo.; Tintic district, Juab and Utah counties, Utah; Tombstone, Cochise County, Ariz.; and Pioche, Lincoln County, and Eureka, Eureka County, Nev.; but many other deposits are known. In most of the districts these ores contain an admixture of more or less manganese oxide. Some of the Leadville ores are so rich in manganese that they are used in the manufacture of spiegeleisen. For the most part, however, these ores are used as flux in copper and silver smelters in the districts in which they occur.

Bog ore. Bog iron ores are found in scattered deposits in many localities in the Western States, and were among the first iron ores mined in this region. The following are the principal known deposits: Wickes, Jefferson County, Mont.; Titania Placer and Geneva Gulch, near Webster, Park County, Del Norte, Rio Grande County, Ophir, San Miguel County, Marshall Pass, Saguache County, Williams Creek, Huerfano County, and Crested Butte, Gunnison County, Colo. Small deposits occur elsewhere in many of the Western States. Bog ores are usually in the form of surface deposits varying up to 10 or 15 feet in thickness but having a large horizontal extent, locally covering many acres. The ores are soft and porous and usually of low grade. In some places, as at Wickes, Mont., they contain a large percentage of bog manganese.

Miscellaneous brown-ore deposits.-There are many small deposits of brown ore throughout the Western States which have not been studied in sufficient detail to be definitely classified. Many of them belong to the preceding classes; others are replacements or concentration deposits.

The following are some of the best known localities:

In Colorado small bodies of limonite occur in Gibson Hill and Nigger Hill, near Breckenridge, in Summit County. A small deposit of hard limonite is found on the hillside back of the Hotel Colorado, at Glenwood Springs, in Garfield County. Several deposits of brown ore occur about 6 miles west of Villa Grove, toward Bonanza, in Saguache County. A deposit at Orient, Saguache County, has been worked for many years and is now nearly exhausted. The ore is limonite, which has resulted from the oxidation of bodies of pyrite, and it is expected that more and more pyrite will appear with depth. The Bennett ore body, which is about 3 miles south of the Orient mine, contains similar ore in the upper portion. Below water level, however, it consists of nearly pure pyrite.

In New Mexico a body of soft limonite 2 to 4 feet in thickness occurs about 8 miles northeast of Glorieta, in San Miguel County. The ore has been mined and used for flux in lead smelters.

In Utah, about 20 miles north of Vernal, near the Utah-Wyoming boundary, in Uinta County, there is a body of manganiferous limonitic iron ore 3 to 8 feet in thickness traceable for several hundred feet along the crest of a hogback. The country rock is sandstone of probable Mesozoic age. Deposits of limonite occur at Willard, Willard Canyon, and North Ogden Canyon, north and northeast of Ogden, and in Cottonwood Canyon, southwest of Ogden, in Weber County. Limonite occurs along Grouse Creek, in the extreme western part of Boxelder County, and the deposits extend over into Nevada.

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Manganiferous brown ore is found in small quantities near Frisco, in
Beaver County.

In Nevada brown-ore deposits are reported from Montello, Cobre, and Moor, Elko County, and from Winnemucca, Humboldt County. In California brown-ore deposits occur at Campo Seco, Esmeralda, and Murphy, Calaveras County; at several localities in San Benito County; and near San Luis Obispo, San Luis Obispo County. The last-named deposit is in the form of a vein having an average width of about 10 feet and traceable for nearly a mile.

In Washington limonite ores are found near Trafton, Snohomish County; at Deep Lake, southeast of Northport; and also east of Valley, Stevens County. At the Stevens County localities the ore occurs chiefly as a replacement of limestone.

MAGNETITE.

Contact magnetite.-Contact magnetite deposits are the principal classes of iron-ore deposits in the West. They are widely scattered, but occur chiefly in Colorado, New Mexico, Utah, and California. The following is a list of the principal deposits:

In Colorado they occur at Taylor Peak, Gunnison and Pitkin counties; at White Pine, Gunnison County; and at Calumet, Fremont County.

In New Mexico they occur at Fierro and Hanover, Grant County, and at Chupadera Mesa, Socorro County.

In Utah they occur at Iron Springs, Iron County, and at Bull Valley, Washington County.

In California they occur at Pitt River, Shasta County; at Newton, Nevada County; at Hotaling, Placer County; Eagle Mountains, Riverside County; and at Providence Mountains, Cave Canyon, Iron Mountain, and Iron King, San Bernardino County.

In addition, there are many other magnetite deposits in the West whose exact nature is not known because they have not been scientifically studied, although they are thought to be contact deposits. Many of these are mentioned under the head of "Miscellaneous magnetite deposits."

The contact magnetite deposits of the West are a distinct type, but approach very closely in structure the Cornwall magnetites of eastern Pennsylvania. Only the ores of the Iron Springs district, in Utah, have been studied in detail.

In general the deposits may be said to occur (1) as replacement deposits in limestone or other sediments at or near the contact of an intrusive igneous mass, or (2) in veins within the igneous masses. The igneous rock is generally of a dioritic, granitic, or andesitic character. The sedimentary rock associated with the ore deposits is characteristically limestone, though locally small deposits of ore are found in association with sandstone or shale. The latter are generally in the form of breccia deposits and veins rather than replacement deposits, which is due to the fact that clastic sediments are replaced only with great difficulty, whereas limestones are readily altered.

The deposits near the contact are in the form of lenses, the large diameter of which is parallel to the contact. They vary in length up

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to 3,000 feet or more and in width up to 1,000 feet or more. single deposit may contain 15,000,000 to 20,000,000 tons. They have not been tested to a depth greater than about 150 feet, but from the nature of the deposits they may be expected to extend downward along the contact for great distances. The dip of the ore bodies is roughly the same as the dip of the adjacent contact. The foot wall is generally the igneous mass, but in many places a layer of quartzite, sandstone, or shale intervenes. The hanging wall is limestone, frequently silicified for a considerable distance from the contact with the ore. The minerals associated with the ores are largely metamorphic types, such as garnet, pyroxene, epidote, amphibole, serpentine, apatite, feldspar, and mica. Calcite and quartz also occur abundantly.

The veins of ore in the igneous masses rarely have a greater width than 20 feet but may have a horizontal extent of 2,500 feet or more. As these deposits are usually small, they have not been developed, and their vertical extent is unknown.

Contact magnetite ores are supposed to have originated from a deep-seated source, to have come up through cracks in the igneous mass during its cooling, and to have penetrated the overlying sediments and replaced them. According to this theory, the ore veins in the igneous rock represent the fissures through which the orebearing solutions came to the surface, and the contact deposits represent replacements of the overlying sediments. If this theory be true, it may be expected that contact deposits pass downward into vein deposits and that the latter extend to great depths.

The ore is mostly dense compact magnetite, but in many localities hematite is abundantly intermixed with it. It is usually high in iron, but contains too much phosphorus for a Bessemer ore.

Titaniferous magnetite.-Titaniferous magnetite is known at six localities in the western United States, viz: At Iron Mountain, Laramie County, in Wyoming; at Caribou, Boulder County, Grape Creek, Fremont County, and Cebolla, Gunnison County, in Colorado; and at Tujunga and Pacoima canyons, Los Angeles County, and Beegum, Tehama County, in California. If methods for economical concentration of titaniferous ores are perfected the Iron Mountain occurrence will be of considerable commercial importance. The Cebolla and Beegum deposits also are reported to be of large size. The other occurrences are unimportant.

The ore occurs as dikelike masses, small veins, or irregular patches in basic igneous rocks of the gabbro-pyroxenite-peridotite series. They consist of magnetite and ilmenite with an admixture of silicate minerals common to the associated rocks.

Chromiferous magnetite in central Washington.—A series of deposits of chromiferous magnetite occur along the Wenatchee mountain range in the northern part of Kittitas County, central Washington. The principal rock along this range is a peridotite formation altered to serpentine. This was intruded into earlier sediments and volcanics and has itself been intruded by later and more acid rocks. It is overlain by Tertiary (Eocene) sediments, largely sandstone, and by basalt flows. The formation immediately overlying the serpentine is the Swauk sandstone, which was deposited on its eroded uneven surface. At their contact and within both are found the iron ores. These are in the form of lenses varying from a few feet to 30 feet in

thickness in the lower part of the sandstone and of irregular replacement deposits which extend downward from the lenses into the underlying serpentine.

The ore in the sandstone is oolitic in texture; that in the serpentine is dense and amorphous and breaks with a conchoidal fracture. The oolitic variety is the principal ore in most of the deposits, but in places it has been entirely eroded so that only the replacement

ore remains.

The ore was apparently deposited locally as carbonate or hydrous oxide on the erosion surface of the serpentine, and later was covered with sediments. Subsequently, it was metamorphosed and dehydrated.

The ore is highly aluminous and contains up to 5 per cent and over of chromic oxide, but is by no means a chromic iron ore.

Miscellaneous magnetite deposits.-Magnetite deposits which probably belong largely to the class of contact deposits but whose nature is not known for lack of detailed study occur in Colorado, New Mexico, Nevada, Arizona, and California.

The following are the principal localities: In Colorado, a vein of magnetite 3 to 4 feet in thickness is exposed for several hundred feet on Tarryall Creek above Como, in Park County. In the Capitol and Snowmass mountains in the western part of the Elk Mountains in Pitkin and Gunnison counties, there are several deposits of magnetite, which, however, are practically inaccessible. Near Pitkin and Tincup in the eastern part of Gunnison County, there are several iron ore bodies which are probably similar to those on Taylor Peak and White Pine. In Mineral Basin at the head of Cottonwood Creek in the western part of Chaffee County, a small deposit of magnetite occurs at or near the timber line. Several small deposits are reported from Monarch in the southwestern part of Chaffee County. A deposit of magnetite and hematite occurs in Badger Creek, in the western part of Fremont County.

In New Mexico, magnetite deposits which may become of some importance occur near White Oaks and Ancho and at other localities in the Jicarilla Mountains, in Lincoln County. Minor deposits in New Mexico are reported also from the Zuni Mountains, Valencia County; from the San Mateo Mountains, Socorro County; and from the Tuerto Mountains, Santa Fe County.

In Arizona, siliceous low-grade magnetite bodies occur in the Black Mask group of claims in northern Yuma County, 30 miles northwest of Quartzite.

In Nevada, several important deposits of magnetite occur in the southern part of Humboldt County, some distance east of Lovelocks. They appear to be replacements of basic eruptive rocks resembling schists. More than 30 ore bodies occur, all of which are over 100 feet in length and 20 feet in width. The largest body is 400 feet in length and 250 feet in width. The ore is high-grade magnetite. In the Cortez Mountains in Eureka County, are the Amarillo iron ore deposits. They are low grade, but of considerable extent. Minor deposits occur near Bullion and in the Dolly Varden district, in Elko County.

In California, important bodies of magnetite, which are probably largely of the contact type, are found in Madera and San Bernardino counties. Minor deposits occur in the northern part of Butte County; in Gold Valley and vicinity, Sierra County; in Placer and Eldorado