ing. The undersize of these screens, the under 24-mesh, goes to a bolting machine that makes 9 oversizes of the following screens: 30mesh, 34-mesh, 40-mesh, 54-mesh, and 72-mesh grit gauze screens, and No. 9, No. 10, No. 11, and No. 17 bolting silk; and a tenth product which is the undersize of the last bolting cloth. These products are used in lithographing, as abrasives, and for polishing. A fourth set of rolls is used to regrind sizes that are produced in excess of the demand. All of the apparatus is connected with air suction and the elevators and chutes tightly boxed so as to reduce the dust to a minimum. The power for the plant is steam.

The mill was acquired from the Pitcher estate in 1926 by M. M. Goodman of Baltimore.

Ware mill (Plate V, 9)

A flint mill was operated until about 35 years ago on a small stream south of the county road 1 mile east of Oakland and 14 miles northeast of North Branch, near the western edge of Baltimore County. Only remnants of the stone walls of the building mark the site of the mill. The quartz is said to have been rolled and sieved dry.

CARROLL COUNTY

Maryland Silicate Mills Company mill (Plate V, 10)

The mill of this company which was located at Finksburg station, was sold in bankruptcy in December, 1910, and subsequently dismantled. E. S. Bastin2 states that the quartz was crushed in a jaw crusher and then between crushing rolls and in a centrifugal crusher. It was further ground in continuous feed tube mills and graded to various finenesses by air separators. The flint for this mill was obtained chiefly from the Brauning quarries located 5 miles to the south.

Patapsco Flint Mill Company mill (Plate V, 11)

This mill situated at Hood Mills was operated about 30 years ago by S. P. Dunkel. The flint was obtained from deposits in the neighborhood and from the Annapolis Rock deposit.

2 Bastin, E. S. Mineral Resources of the U. S., U. S. Geol. Survey, 1907, Pt. II, p. 848.

THE CHROME INDUSTRY IN MARYLAND

INTRODUCTORY

Though the element chromium occurs in a number of minerals. chromite or chromic iron ore, is practically the sole commercial source of the metal. The theoretical composition of the mineral is FeO.Cr2O3, corresponding to 68 per cent chromic oxide and 32 per cent ferrous oxide. In many cases, however, the ferrous oxide is replaced in part by magnesia and the chromic oxide by alumina and ferric oxide. In this way, in extreme cases, the chromic oxide content may be reduced to a very low percentage, the iron oxide greatly reduced and the percentages of magnesia and alumina may reach considerable figures. The usual range of chromic oxide in commercial ores is 40 to 60 per cent.

Chromite is an opaque iron-black to brown-black mineral with high luster. It is scratched with difficulty by a knife, yielding a brown streak. The crystal form is the octahedron but it usually occurs massive and breaks with an uneven fracture.

BRIEF HISTORY OF MARYLAND CHROME INDUSTRY

An interesting account of the discoveries of chrome ore in Maryland was written in 1895 by William Glenn.3 Chrome mining in Maryland commenced with the discovery of chromite on the farm of Isaac Tyson, Jr. at Bare Hills near Baltimore at a date usually placed at either 1808 to 1810 or about 1827. From the fact that most of the work at Bare Hills had been done and the workings abandoned for some time prior to 1833, the latter date would seem to be a little too late. The Soldiers Delight region about 10 miles west of Bare Hills and the Reed Mine near Jarrettsville in Harford County were discovered in 1827 and the Line Pit in Cecil County soon after. Even the more remote Montgomery County occurrence was found in this early period. The discoveries were made by Isaac Tyson, Jr. who is credited with having been the first to recognize the mineral and its association with serpentine. Tyson's prospecting was guided also by his prompt recognition of the comparative barrenness of vegetation of the serpentine terrane. His

Glenn, Wm. Trans. Amer. Inst. Min. Engineers, vol. xxv, 1895, pp. 487–492.

keenness in recognizing the geologic occurrence of the chrome deposits and by the aid of this knowledge ferreting out nearly all the known chrome deposits in the belt of serpentine rocks that extends across the State is deserving of great credit.

It seems that in this early period of chrome mining as each new district was discovered it aroused hopes and excitement and the older localities were abandoned in favor of it, only to be again taken up later on as the excitement abated.

The chrome ore mined at the Maryland localities, as well as in the portion of Pennsylvania adjacent to Cecil County where important mines were also developed, was brought to Baltimore; and from 1828 until 1850, most of the world's supply of chrome ore came from this city. In 1848 the larger and richer deposits in Turkish Asia Minor were discovered and exports to Europe began to fall off and practically ceased by 1860. In recent years a small tonnage of sand chrome has been shipped to Europe for special use in high-grade pottery manufacture.

The Tysons did not rest content with securing a virtual monopoly of chrome mining in the United States through their operations in Maryland and Pennsylvania, but also set out to do the same in the chemical industry. In 1833 Isaac Tyson, Jr. made an unsuccessful attempt to establish a chrome plant at Baltimore but finally achieved success in 1845 and the Tyson chrome works monopolized the manufacture of chrome compounds in this country for over 40 years. Repeated attempts to establish competitive plants at Philadelphia, New York, and Boston during 1870 to 1880 met with disastrous financial failures until finally early in the next decade a successful plant was established at Philadelphia. The Tysons, however maintained the prestige of their Baltimore chrome works until they sold out to the Mutual Chemical Company of America in 1908 and finally withdrew from the chrome business.

After its early boom chrome mining in Maryland seems to have suffered a considerable decline about the middle of the last century. Toward the close of the sixties and during the seventies operations were again active at most of the Maryland deposits. Large quantities

of ore were mined, particularly at Soldiers Delight and at the Reed mine in Hartford County, and sand chrome was produced at a number of localities in Baltimore, Harford, and Cecil counties. In the late seventies the Tyson Mining Company commenced operations in California and shipped their ores to Baltimore via Cape Horn at a cost delivered of $35 to $40 per ton. As the Maryland industry became almost extinct in the next few years the deposits were either unable to compete with California ores at that price or were looked upon as exhausted. Since about 1880 there has been only a small and irregular production of sand chrome and, except a small amount between 1917 and 1925, none of rock chrome in Maryland.

PRODUCTION

Though chrome mining in Maryland has been in a state of decline for a half century the uses and demands for chrome ores have greatly expanded and the world's production has been increasing. The production of the United States has also been on the decline and this country has been dependent on foreign supplies. During the war the domestic production was considerably increased but Maryland was but a small contributor to the increase. Under post-war conditions chrome mining in Maryland and in the United States again decreased almost to the vanishing point, as is shown by the following statistics: