them, extending for about a quarter of a mile on each side of the center of the section.

There is another range of them near the center of the southwest quarter of Section 1, and a third line near the quarter-posts of Sections 1 and 12. The largest of these sinks is an isolated one near the center of the southeast quarter of Section 1, which is as much as fifty feet in diameter and twenty feet deep. In this one the wall rock of the fissure could be very planly seen on the south side. The difference is that these sinks mark the line of large open crevices in the rock beneath them. No prospecting for ore has been done in them, although the suggestion has been reasonably made that the indications are favorable. The sinks are not confined to the Galena limestone, and an exceptional one in the St. Peters sandstone is noted on the southeast quarter of Section 14, Township 5, Range 2 west, although less notable ones occur in the Niagara limestone. "Soil and Subsoil.-The quality of the soil of the lead region is chiefly dependent on the character of the subjacent formation. The subsoil appears to be derived directly from the decay and disintegration of the strata, of which it is the residuum. South of the principal water-shed. the subsoil is clay, almost without exception, having a thickness of from three to six feet, depending on the configuration of the underlying rock formation. This is the average thickness, on comparatively level land; on side hills it is usually much thinner, the greater part having been washed down in the valley below. The clay soils and subsoils appear to consist chiefly of those portions of the overlying Galena limestone, and earthy Cincinnati shales, which being insoluble in water were not removed by the gradual process of denudation.

"The amount of lime, magnesia and alkaline earths in the subsoil and soil, together with the vegetable mold in the latter, constitute a soil, which, in its virgin state, is unsurpassed for richness and fertility. The number of successive wheat crops which have been raised, without regard to rotation, on some of our prairie farms, attest its native strength; as, also, the marked decline in fertility of the soil when this has been done, shows the inevitable retribution which follows the practice. Exceptions to the clay soil, usually found in the country covered by the Galena limestone, are found in the eastern part of La Fayette and frequently in Green County, where the soil is quite sandy, owing to the disintegration of calcareous sand layers frequently found there in that formation. A few localities are cited below, where the sand was so abundant that the formation might have been considered a sandstone, were it not for the occasional outcrops of Galena limestone in place.

"The agencies of the glacial period do not appear to have had anything to do with transporting the component meterials of the soil, and although a slight transportation has taken place, it is always merely local. For instance, in the valleys of the creeks which lie in the St. Peters sandstone, the soil is usually a rich clay loam, richer in fact than that of the adjacent ridges, because the best parts of the upland soils have been washed down and distributed over the surface of the valley.

"A similar transportation may be observed in passing up any long and moderately steep hill, which includes several formations, such hills being very common north of the principal watershed. Let us suppose one, whose summit is composed of Galena limestone, and whose base lies in the Lower Magnesian. Scattered about the base will be seen many loose pieces of Lower Magnesian limestone, mixed with less numerous bowlders of St. Peters sandstone; still less numerous and smaller pieces of the buff and blue (Trenton) limestone, while fragments of the Galena limestone will be comparatively rare. On ascending the hill and arriving at the St. Peters, fragments of Lower Magnesian will no longer be seen, while those of the upper formation will become larger and more numerous. On arriving at the buff limestone, the fragments of St. Peters sandstone will also have disappeared; fragments of blue limestone will be very numerous and easily recognized by their white color and their general rounded and worn appearance. On reaching the summit of the hill, no fragments of stone will be found, except such as are derived from the subjacent Galena limestone. One prominent feature of the soil will be the prevalence of flints, which are nearly indestructible, and often form a large component part. From the arrangement of the surface soil and fragmentary rock, it is evident that the rock of any formation is never found above the level from which it was detached.

"Brick Clay.--Clay suitable for making brick is found in many parts of the lead region, Mineral Point being one of the important localities. The clay sought is usually of a grayish yellow color which becomes red on burning. It appears to have been formed in the same manner as other portions of the soil, as already described. The origin of the clay of which the brick are made is a matter of some doubt. It has not exactly the appearance of a drift clay, and if not, its situation indicates that it must have undergone some subsequent re-arrangement."

THE LEAD REGION DESCRIBED.

FROM MOSES STRONG'S REPORT.

Boundaries and Area.-In Wisconsin, the lead region may be said to be bounded on the north by the northern outcrop of the Galena limestone, running parallel to the main water-shed from the Mississippi to the Blue Mounds, as already described; on the west by the Mississippi River; on the south by the State line; on the east by Sugar River. These limits include all of the lead region which has ever been productive, as well as much that has never as yet proved so. The area thus included. which has been, or may hereafter become, productive, is necessarily that of the Galena limestone, which is about 1,776 square miles.

Explanation of Mining Terms.-For the enlightenment of the readers who are unfamiliar with mining terms, the following short explanation of expressions, most frequently used in the lead region, is offered.

Range. This is probably the most indefinite term in use, and, at the same time, one which is universally applied. First. A range denotes a single, or several, parallel crevices, containing useful ores or minerals; vertical, or approximately so; seldom more than a few yards apart; sometimes, but not necessarily, connected by quartering crevices. Its length may vary from a few hundred feet to a quarter of a mile or more; in short, so far as the crevice or crevices have been connectedly traced, or there is a reasonable probability of such connection. Thus, different parts of the same range often have different names given them before the connection between them is proved. This is a fruitful source of confusion. Second. The term range is also applied to horizontal bodies of ore, of which there may be one, or several, superimposed upon one another; sometimes, but not necessarily, separated by unproductive layers of rock, limited in length in the same way as a vertical range.

Crevice. This term denotes a fissure in the rock, vertical or nearly so, but a few inches in width, of indefinite length, which may or may not be filled with ores or minerals. When a crevice becomes very small, less than an inch in width, it is called a seam.

Vein is a term little used; it denotes the filling of ore and accompanying minerals, or either found in a crevice.

Lode or Lead are words usually substituted for vein; they are, however, generally applied to ore deposits found either in crevices or openings.

Swither. A metalliferous crevice, making an angle with the principal vein or lode; sometimes called a quartering crevice.

8 o'clock, 10 o'clock, etc.-Ranges whose course bears toward the sun at those hours of the day.

Openings. They are of two kinds, vertical and horizontal. First. Vertical openings are known as crevice openings, which are mere enlargements of the crevice in certain parts, these being sometimes co-extensive with the vein in length, and sometimes mere local enlargements. There are in the same crevice frequently several openings, situated one above the other, separated by beds of unproductive rock. Crevices vary in width from one to several feet. When very wide and high, they are sometimes called tumbling openings. Second. Horizontal openings are large, irregular spaces between the strata which contain the lode. Such openings are usually from one to four feet high, and are frequently superimposed upon one another, separated by an unproductive rock, called a "cap. The cap of one opening being frequently the

"floor" of the one above it.

66

Pockets are small irregular cavities in the strata, in which ore is frequently obtained.

Chimneys are irregularly shaped vertical holes found in crevices; sometimes connecting openings, and at others extending from the surface of the ground to some particular stratum of rock.

Sheet. This is a term usually employed to designate a solid body of ore, exclusive of other minerals, which may fill a crevice or opening. A sheet is said to "pitch" when it inclines considerably from the perpendicular.

Gouge. This is the soft rock or clay frequently found between the sheet and adjacent wall-rock.

Bar. The term denotes a band or belt, of very hard and unproductive rock, crossing the crevices and sheets. In crossing a bar, all sheets become less productive, and are sometimes entirely lost, the crevices usually dwindling to mere seams. Their width varies from a few feet

to many yards.

Wash dirt is the name given to the small ore, as it first comes from the mine, mixed with small pieces of rock and clay.

Pipe Clay.-A light-colored plastic clay, frequently found in the openings and crevices. Drift.-An underground gallery or roadway.

MINERALOGY.

There does not appear to have been any absolute and unvarying order in which the minerals of the lead region were deposited in the mines. The following conclusions are derived from the inspection of the ore as it occurs in place in the numerous mines visited, and from the examination of a great number of specimens; and it is assumed that when crystals of one mineral are coated or covered with another, the overlying one is the more recent. The minerals appear to have been deposited in the following general order:

The order above given, however, is subject to very numerous and important exceptions, and is more particularly applicable to crystallized specimens than to heavy ore deposits. Large bodies of ore frequently consist of galentine, sphalerite and pyrite, so mingled together that no order of deposition can be ascertained.

In general, it appears that the sulphurets of the metals were deposited first, and that the carbonates have been generally, if not invariably derived from them. Carbonate of lead (cerussite), when found crystallized, always occurs in connection with galenite; and carbonate of zinc (Smithsonite) is so frequently found graduating into the sulphuret (sphalerite) as to leave but little doubt of its origin from that mineral.

It seems not improbable that the formation of the carbonate of zinc may even now be taking place in the ground to quite a large extent, especially in such deposits as are not below the water-level, or are only periodically submerged.

It is a well-known fact that the drybone diggings are usually comparatively free from water, and that the zinc ore below the water-level is usually blende (sphalerite) with but little admixture of the carbonate. As the level of the water in the ground becomes gradually lower, and it is a well known fact that it does, the atmosphere, together with surface water charged with carbonic acid, is permitted to act upon the blende, and a transformation from the sulphuret to the carbonate is the result.

The association of calcite with other minerals is such as to indicate that it must have been formed in crystals during at least two different periods. Stalactites of recent origin are found in the mines, which on being fractured show a distinct crystalline structure, and large planes of cleavage.

The following is a list of the minerals known to occur in the lead region, arranged according to the system adopted by Prof. Dana, in his "Mineralogy:

Sulphur.-Native sulphur is found, but seldom in the lead region; its presence is usually due to the decomposition of iron pyrites. It is usually found in a pulverulent form. Some pieces weighing as much as an ounce were seen in a cabinet at Hazel Green, which are said to have been obtained from a small sheet in some of the Buncome mines. It is said to be not uncommon in this vicinity. Other localities where it is found are Mineral Point and the Crow Branch diggings.

Bornite. Variegated or purple copper ore. Composition-Copper, 62.5; iron, 13.8; sulphur, 23.7. This is quite a rare mineral. A few pieces have been found in the copper diggings near Mineral Point; it has never been found here crystallized, but always massive and in small pieces.

Galenite.-Composition-Lead, 86.6; sulphur, 13.4. This is the only ore of lead found in sufficient quantities to be of economic value. It is universally known in the lead region as "mineral." It frequently occurs in distinct crystals, either as a cube or some modification of it. Octahedral crystals are quite rare, but are occasionally found, especially in the carbonaceous shale of the southern part of the region. Usually, however, galenite occurs massive, with a very distinct cleavage. Freshly broken surfaces have always a bright steel color, which speedily tarnishes on exposure to the air.

Sphalerite.-Blende or black-jack. Composition-Zinc, 67; sulphur, 33. This is one of the most abundant minerals in the lead region, besides being of great economic value as an ore of zinc. It is almost invariably found as an associate vein-mineral in the horizontal deposits of lead ore. It is usually found massive and compact, of a dark-brown or black color, due to a small portion of iron contained in it, and more or less mixed with gelanite. The lead region has never afforded a perfect crystal of blende, although many specimens are found with small and imperfect crystalline faces. The fractured surfaces of such specimens usually have a

resinous luster.

Pyrite.-Composition-Iron, 46.7; sulphur, 53.3. This is the most common vein-mineral found in the mines. It is universally met with in veins, lodes or other deposits of ore, and in many cases impregnates the rock when all other minerals are absent. In crevices it frequently appears to have been the first mineral deposited. It is usually found massive, although handsome crystallized specimens are frequently obtained from the mines. In crystals it usually assumes some modification of the cube, the octahedron being quite frequent. It also occurs in radiated and reniform masses. It has never yet been considered of any economic value in the lead region, and as it is so much mixed with rock it is doubtful if it could be profitably separated, except by the natural process of disintegration, to which some varieties are liable when exposed to the air. The Crow Branch diggings and the Linden mines afford large quantities and good specimens of this mineral.

Marcasite.-Composition-Iron, 46.7; sulphur 53.3, or same as pyrite. The difference between this and the preceding is but slight, and chiefly due to crystalline structure; the former belonging to the mono-metric and the latter to the trimetric system. It is somewhat lighter colored than pyrite, and decomposes more readily in the air. It is quite a common vein mineral, and occurs in globular and cockcomb shapes. It is abundant in the New Diggings district. It is difficult to preserve specimens of this mineral, longer than a few months.

Chalcopyrite.-Composition-Copper. 34.6; iron, 30.5; sulphur, 34.9. This is the principal ore of copper in the lead regions, and is most abundantly found in the vicinity of Mineral Point. It usually occurs massive, frequently mixed with pyrite; small and indistinct crystals are occasionally found.

Hematite.-Composition-Iron, 70; oxygen 30. Impure arenaceous varieties of this mineral frequently occur, nowhere, however, sufficiently rich or abundant to be of any economic value. It seems to be chiefly due to the decomposition of pyrite, and is most common as the ferruginous sandstone concretions in the upper beds of the St. Peters. It is also frequently found as ocher, with other vein-minerals, especially in the flat openings.

Oxide of Manganese.--A substance consisting of manganese with a little oxide of iron, zinc, and traces of magnesia, according to an analysis of Dr. Bode, of Milwaukee, is found in crevices in the Trenton limestone, in some diggings situated on Section 11, Town 4, Range 1 east. The mineral is as light as cork; color brownish-black, sub-metallic luster and streaks; soils readily, and is infusable. It is very soft, and does not occur crystallized. It has a structure in thin parallel layers, resembling wood.

Calamine.-Composition-Silica, 25.0; oxide of zinc, 67.5; water, 7.5. This mineral is of very rare occurrence in the lead region. It is found in small, drusy crystals; coating, Smithsonite. The crystals are very brittle, colorless, and have a vitrious luster. It is found near Mineral Point.

Barite.-Composition-Sulphuric acid, 34.33; baryta, 65.67. It occurs usually white and massive, but sometimes in lamellar and crested forms. The only place where it was found in distinct crystals, was in the railroad cut at Scales Mound, where it occurs in small cavities, as small but very perfect transparent crystals, associated with dolomite and pyrite. It is not a very abundant mineral, but is found in several of the mining districts, especially Dodgeville and Min

eral Point.

The following is an analysis by Mr. E. T. Sweet, of a specimen from the southwest quarter of Section 6, Township 5, Range 3 east, in Van Matre's survey:

Anglesite.-Composition-Sulphuric acid, 26.4; oxide of lead, 73.6. Traces of this mineral are reported as occurring in some of the mining districts, but no specimens have as yet been obtained. It probably originates from the decomposition of galenite.

Calcite.-Composition-Carbonic acid, 44; lime, 56. This is a vein-mineral, common to all the deposits of ore, whether in crevices or openings. It occurs crystallized in modified rhombohedrons and scalinohedrons. The variety known as Dog-tooth-spar is a very frequent form, especially in the Shullsburg and Linden districts, which affords very handsome cabinet specimens. The Mineral Point district affords handsome rhombohedrons, and the Linden mine affords handsome twin crystals of calcite set in sphalerite (blende). It also occurs there, rarely, as a pseudomorph, after marcasite, and has then a radiate or divergent form.