stone would have to be brought, in most cases, from distances varying from fifty to a hundred miles. The ores are near the surface, however, and easily mined; and there is a large amount of timber fit for making charcoal in the vicinity, so that it is not impossible, in view of these advantages, that a small iron industry might, under favorable conditions, be supported on the better grades of ores of the region. The good ores are scarce, however, and under any circumstances the industry would be small.

"The commercial possibilities of the Arkansas iron region may be briefly stated as follows:

"The ores are mostly brown hematites, though small quantities of spathic and magnetic ores also occur. Most of the brown hematites, if not all, are non-Bessemer in character, the phosphorus ranging generally over 0.05 per cent; the iron ranges from 35 per cent to rarely over 55 per cent; the silica is usually, though not always high, ranging from 2 per cent to over 75 per cent; the sulphur ranges from 0.04 to over 1 per cent; there is usually a trace of manganese and sometimes enough to allow the ore to be classed as a manganiferous iron ore; none of the ores, except that of Magnet Cove, have yet been found to contain appreciable quantities of titanium. The only ores in the State that could, even under the most favorable circumstances, be worked on a commercial scale are some of those in northeastern Arkansas and a few of the deposits of the Ouachita Mountains and of southern Arkansas. Of these three regions, northeastern Arkansas is the only one which offers favorable conditions for iron mining and manufacture, and even there the industry, if established, would be limited.

"The conclusion to be drawn, therefore, is that the quality and the quantity of the Arkansas ores, the position of the deposits as regards transportation, the distance of the markets, and the proximity of much better ores in Missouri, all point to the fact that there is, at present, no good field for an iron ore mining industry in Arkansas except possibly in the northeastern part of the State."

Production. Two small bloomaries were operated in northern. Arkansas for a short time prior to 1860. These were built to supply a local demand on account of the difficulty of transporting heavy material into the region at that time. Besides these, no iron ore has been used industrially in the State up to the present. Prospecting, however, has been done and continues.

1.

Bibliography of Iron

1892

Penrose, A. F., Jr., "The Iron Deposits of Arkansas."-Annual Report of the Arkansas Geological Survey for 1892, Vol. I. Now out of print, but may be consulted in public or scientific libraries.

LIMESTONE FOR BURNING

Composition-Chemically, lime is calcium oxide, but commercially the term is applied to the product of complete calcination of a "limestone" which may vary from a calcium carbonate to a dolomite or calcium, magnesium carbonate. Thus commercial lime may contain as high as 45 per cent magnesium oxide, as well as such impurities as silica, iron oxide and alumina.

Lime is sold in two forms: (1) Quick lime (calcium oxide) and (2) hydrated lime (calcium hydroxide). Hydrated lime is formed. by adding the requisite amount of water to quick lime. "Air-slaked" lime has absorbed carbon dioxide from the air and thus returned to its original composition, calcium carbonate.

Commercial limes are classed according to their content of calcium oxide and magnesium oxide, as follows:

High calcium lime: Not less than 90 per cent calcium oxide. Calcium lime: Not less than 85 per cent nor more than 90 per cent calcium oxide.

Magneisian lime: Not less than 10 per cent nor more than 20 per cent magnesium oxide.

High magnesian lime: Not less than 25 per cent magnesium oxide.

Total impurities (exclusive of carbon dioxide) should not be over 5 per cent in selected lime or 72 per cent in run-of-kiln lime.

Theoretically, one ton of pure calcium limestone should yield about 0.54 ton of pure lime and one ton of pure dolomite limestone should yield about 0.52 ton of dolomite lime.†

Uses. The uses of lime are so numerous and varied that it would be impracticable to attempt to enumerate and describe even all of the principal uses. About one-half of the lime produced in this country is used by the building trades, about 10 per cent for agricultural purposes, and the remainder in the chemical trades. In Arkansas, the major use could well be for agricultural purposes; however, the principal uses in the State at present are for building purposes, and lime used for agricultural purposes is very small in amount.

The limestones in the Boone chert vary greatly in composition, ranging by close gradations from chert to almost pure calcium carbonate. However, in nearly all places where the large beds of limestone occur, it is comparatively pure carbonate of lime. Some nodules or lenticular masses of chert occur in the heavy beds of limestone, but in no instance was there any considerable quantity of silica found diffused through the bed of limestone. The whole series in fact might be divided into (1) chert almost free from lime, (2) calcareous chert or siliceous limestone, and (3) comparatively pure limestone. The following analyses show specimens of these three classes:

"Non-metallic Minerals," p. 310, by R. B. LaDoo, published by McGraw-Hill Book Company, 10th Avenue at 36th Street, New York, N. Y.

Mill Creek,
W.. Sec.

18

Per Cent

16 N.,

13

For classification and distribution of limestones of Arkansas, see "Building Stones" and "Mineral Fertilizers."

Producers

The lime burning plants in operation in Arkansas are as follows: 1. St. Joe Lime & Stone Company (burnt and unburnt limestone products), St. Joe, Ark.

2. Ozark White Lime Company (manufacturers of burnt lime and hydrate), Fayetteville, Ark.

3. Batesville White Lime Company (manufacturers of burnt lime and hydrate), Batesville, Ark. Plants at Limedale and Ruddles, Ark.

*Arkansas Geological Survey.

Bibliography of Limestone

(See "Limestone" under "Mineral Fertilizers")

Valus

$129.20

100.90 $250.10

Value

$152.00

189.95

182.10

241.93

$766.98

$249.61

LITHOGRAPHIC STONES

A lithographic stone is a smooth, more or less impure, evengrained, compact limestone which is usually of a buff or drab color and has a conchoidal fracture. It must be soft enough to work readily under the engraver's tool without chipping or leaving ragged edges; it must be porous enough to absorb ink, and tough enough to stand the necessary pressure of the printing press.

Analyses of lithographic limestones which are said to be successful follow, with one analysis from a sample of Lafferty Creek, Izard County, Arkansas, for comparison:

Occurrence. The Izard County limestone is a smooth, finegrained, compact, homogeneous, non-fossiliferous, evenly-bedded limestone, breaking with a conchoidal fracture. A quarry was opened on the Warden property on West Lafferty Creek, Izard County, and for a while blocks of stone were quarried for lithographing purposes. When put to the actual test, it was found that fine crystalline particles which sometimes occurred as single crystals, and sometimes as hair-like veins, splintered under the engraver's tool and made ragged edges, rendering the stone useless for lithographic work.

As yet no other attempt aside from the one on the Warden property, involving an expenditure of about $10,000.00, has been made. to commercially produce lithographic stones in Arkansas.

Should a bed of stone suitable for lithographic work be found. in the Izard County limestone, the supply would be abundant, as the Izard limestone occurs in five counties in northwest Arkansas.

Bibliography of Lithographic Stones

1890

Hopkins, T. C., "Marbles and Other Limestones."-Annual Report of the Arkansas Geological Survey for 1890, Vol. IV., pp. 47, 55, 76-77, 109, 111112, 233.