Salisbury Mining District, USAi

Regional Level Types
Salisbury Mining District	Mining District (Abandoned)
USA	Country

Limonite.—This species includes all the ores which have heretofore afforded iron to commerce in this State, if we except the unimportant quantity derived from the magnetic iron-sand above mentioned. It presents a number of mineralogical varieties, depending on diversities in mechanical composition, the intermixture of foreign species, and rarely of organic impurities. Among these varieties the following may be enumerated as the most important: fibrous brown hematite, compact hematite, ochrey brown iron ore, and bog iron-ore.

Fibrous brown hematite consists of 82 peroxide of iron, 14 water, 2 oxide of manganese and 1 silica, in the hundred parts, while bog iron-ore contains from 40 to 50 p. c. of peroxide of iron, the other ingredients being silica, alumina, water and oxide of manganese, with frequent traces of phosphoric acid.

The fibrous brown hematite, compact hematite, and the ochrey mixtures of the two, are generally confined to primitive rocks, as gneiss and mica-slate. They afford materials for very large iron-works in many countries, and are universally regarded as the best ores for yielding a malleable iron, and for being easily converted into steel. Although these ores (which may be referred to, under the general name of hematite) are confined to a limited district of the State, they nevertheless appear to constitute its richest metallic resource.

The iron which comes into the market under the name of “Salisbury iron” is smelted from limonite ores mined in northwestern Litchfield County, Connecticut; Berkshire Co., Mass.; and portions of Dutchess and Columbia counties in the State of New York. The ore was first mined, and much the largest amount of ore has now for a long time been obtained at mines situated within the town of Salisbury, Connecticut. No geological report seems to have been made upon this ore district as a whole, though many widely scattered papers have made reference to it, and together constitute a considerable body of scientific information.

In spite of the rather low grade of the ores (40 to 50 and exceptionally 55 to 57 per cent. of metallic iron) and the recent vast development of iron mining within the Lake Superior region, the Salisbury mines continue to be worked. This is largely due to the peculiar properties of the ore; particularly its high content of manganese and its low percentage of phosphorus, and to the methods of smelting and founding which are employed; the furnaces of the Salisbury and Richmond regions being among the few still left in America which use charcoal as fuel. The pig iron produced from these ores is especially adapted to the manufacture of car wheels, since it is of sufficient strength to resist the strains and shocks to which the wheel body is subjected, and has further the property of taking a deep chill, so that the tread and flange of the wheel can be made to withstand the wear upon them. That the fame of the Salisbury iron for this purpose is well founded has been amply demonstrated by tests carried out by Thurston and others.

HISTORY.

Iron was mined in Salisbury at least as early as 1734, the pioneer forge, with a capacity of one hundred and fifty pounds of iron for each charge, having been erected in that year in the village of Lime Rock. The ore for it was furnished from the “Davis” or “Forbes” pit at Lakeville, then known as the “Hendricks.”

In 1781 a forge had been erected at Mount Riga on the summit plain of the Mount Washington mass, nearly one thousand feet above the mines in the valley.

In 1830 the first foundry for remelting pig iron was built at Lime Rock and soon came into the possession of Mr. Milo Barnum, the founder of the Barnum Richardson Company. This company now controls all of the ore that is mined within the Salisbury district proper, and has also an interest in the Richmond Iron Company, which operates the “Cone” mine in the Richmond district.

The mines at Salisbury, which are known as the “Old Hill,” the “Chatfield” and the “Davis,” were acquired by the Barnum Richardson Company, and have now been worked for periods of about one hundred, seventy-five and one hundred and seventy years respectively. Other mines of the region were soon purchased by the company, the greater number being near the eastern, southern or western margins of the great elevated mass situated near the common boundaries of Connecticut, Massachusetts and New York, and generally known as Mount Washington. As time went on the Barnum Richardson Company acquired many other properties in the vicinity, though most of them have now been abandoned and are so flooded with water as to afford few facilities for inspection.

Charcoal blast furnaces for the smelting of the Salisbury ores have been situated at Lime Rock, Falls Village, East Canaan, Chapinville, Cornwall Bridge, Huntsville, Amenia, Sharon Valley, Millerton, Mount Riga and Copake, all in or near the mining district....Only the furnaces at Lime Rock, Canaan, Richmond and Van Deusenville are now in use.

DISTRIBUTION OF THE MINES.

The greater number of the iron mines of the Salisbury district are located either at or near the boundary of the areas of Hudson schist with those of the Stockbridge dolomite. In this regard they have the same position as most of the other limonite deposits which have been opened along the base of the Appalachian Mountain system from Vermont to Alabama. A further fact of distribution which is of much significance is the arrangement of the mines of the Salisbury group about the base of the elevated area of Mount Washington. This mountain mass rises abruptly to heights of sixteen hundred to eighteen hundred feet above the level of the valley surrounding it. Its greatest length is seventeen miles, and its maximum breadth about six miles (see Fig. 11). The more important of the exploited ore beds form a nearly continuous series encircling the mountain mass at its base.

As properly included with the group of mines bordering on the Mount Washington mass should be mentioned those which extend southward along the line of the Ten Mile River and the Harlem River Railroad; which mines, with the last nine of the above, form a linear series which may be conveniently termed the Ten Mile series...

COMPOSITION OF THE ORES.

General Statement. - The ores of the Salisbury district have been described as largely limonite, with which is associated a small amount of turgite, and in variable quantity ores of manganese. From certain of the mines, notably the “Ore Hill,” “Amenia,” and “Copake” mines, the so-called “dead-head” or “white horse” has also been mined. This latter material, generally described as iron carbonate, is usually but an impure variety of that mineral, since it generally contains considerable silica and a sericitic or talcose mineral.

The superiority of the Salisbury ores is largely to be ascribed to the low content of phosphorus and the high content of manganese; and these qualities are enhanced by the method of smelting in charcoal furnaces.
...individual mines have their peculiarities of composition. The “Davis” ore is particularly valuable because of its high content of manganese, this is to a less extent true of that from the “Ore Hill” mine. Richest of all, in this constituent, however, was the black ore of the “Chatfield” mine, and the genuine manganese ore from the “Scoville” pit. It thus appears that the ores richest in manganese are distributed in the bodies which occur along the eastern and southeastern base of the Mt. Washington mass. The mine at South Kent was abandoned on account of the high content of phosphorus.

The fact that zinc is associated in minute quantities with manganese in nature has been illustrated by the operation of the Salisbury smelters, even though it has not been indicated by the chemical analyses. The tendency of this element to sublime results in its collection in the throats of furnaces, from which it is recovered when the furnaces are “blown out.”