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 71⁄2 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.

Near Victor P.

0.

13 N., 7 W., Sec.
10-Per Cent

Mill

18

Creek, 16 N.,

W.,

Sec. 13

Per Cent

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.

4,992.20

Bibliography of Limestone

(See "Limestone" under "Mineral Fertilizers")

Denieville, Independence Co. Per

Cent

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.

MANGANESE

Composition.-Manganese is a metallic element which has about the same specific gravity as iron. It is used principally as an alloy. with other metals.

Spiegeleisen, an alloy of iron and manganese, contains under 20 per cent manganese, and ferro manganese has from 20 to 90 per cent. Other alloys are with bronze, copper, aluminum, zinc, tin, lead, magnesium and silicon.

The manganese ores found in Arkansas have been principally oxides of manganese known as psilomelane, braunite, hausmanite, pyrolusite and wad. The first three are the most commonly encountered. These ores generally contain from 45 to 52 per cent of manganese and sometimes slightly over 60 per cent.

Uses. Manganese oxide is used widely in the chemical trades as a coloring agent in cloth printing and dyeing, making of pottery, bricks and paint, and in the manufacture of dry cells.

The Arkansas ores are used almost entirely in the manufacture of ferro manganese, spiegeleisen, and manganese pig ore.

The price of manganese ore depends upon the percentage of metallic manganese in it. The present price (November, 1926) is between 32c and 34c for each percent of manganese per long ton of ore containing 47 per cent manganese, and 38c to 40c for each per cent of manganese per long ton of ore containing from 54 to 55 per cent metallic manganese.

Occurrence. Manganese is found in several localities in the State, by far the most important of which is the area known as the Batesville area of about 100 square miles, located in northwest Independence County, Southeast Izard County and northeast Stone County. Other localities of less importance are in Pulaski, Saline, Garland, Hot Spring, Montgomery; Pike and Polk Counties. These last mentioned localities are known as the West Central Arkansas district. There have been as many as 100 manganese mines in operation in the Independence district and five have been reported in the Montgomery, Pike and Polk County district. In addition to these, there have been over 100 prospects in the Batesville area and nearly an equal number in the West Central Arkansas district.

The Batesville District

In the Batesville district the manganese ores are found in irregular fragments and nodules which have probably been concentrated from the Cason shale formation of Ordovician age. These lumps of ore are found in this shale and in residual clay beneath the shale. Both the clay and the manganese ore nodules are probably residual products of the decomposition of the Cason shale. The West Central Arkansas ores are found in pockets scattered through the Arkansas novaculite formations which are probably of Devonian age. The West Central Arkansas deposits, however, although containing large amounts of ore are not sufficiently concentrated to permit profitable mining during normal prices of manganese