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Fort Hays Chalk

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Bowles (1942, p. 3) states: "Whiting is finely ground, pulverized, powdered or chemically precipitated calcium carbonate of good white color." The United States Bureau of Mines defines precipitated whiting as being prepared by reaction of milk of lime with carbon dioxide, or by some similar chemical reaction (precipitated chalk). Chalk whiting is prepared from crude chalk by mechanical settling. Most of the whiting plants are in eastern coastal States.

The uses of whiting are listed below (Lamar and Willman, 1938, p. 44).

As a constituent of . . .

As a filler in . . .

For . . .

Whiting is used in the following industries: structural iron, ship-building, locomotive works, file manufacture, explosives, medicines, leather, printing, shoe manufacture, roofing cement, and chemical manufacture.

Fifty percent of the imported chalk and whiting is used by the paint industry, 35 percent by the rubber industry, and 10 percent by the putty trade. Additional uses of whiting listed by Bowles (1942, p. 5) are in soap, dentifrices, sealing wax, acoustic tile, roofing, calking compounds, insecticides, gypsum plaster, cosmetics, and paper plastics.

Specifications for chalk to be used in whiting

The specifications for whiting vary considerably depending on the use. Specifications are lacking except in a few instances. Generally the color, fineness, and freedom from grit are important in determining the quality. However, some standard methods to determine certain specific properties have been established. Sales are based largely on samples.

Particle size (Wilson and Skinner, 1937, pp. 39-40) plays an important role in such properties as tint, brightness, hiding power, and oil absorption of paint pigments and fillers. The fineness of the filler in the rubber industry determines the smoothness of the finished product and to some extent the amount of latex necessary. It has been reported (Wilson and Skinner, 1937, pp. 39-40) that rubber has been given high tensile, tear, and abrasion resistance by precipitated calcium carbonate so fine that 98 percent is less than 0.4 microns in diameter. Chalk grains studied by us range from 0.2 to 0.55 microns. Precipitated whiting made from this chalk would have a smaller grain size. Abrasion and rapid wear of the internal structure of rubber particles subject to movement and stress is caused by coarse gritty particles. Fillers in cosmetics and dentifrices require a fine smooth texture. Tables 7 and 8 give the chemical requirements for the rubber industry and ceramic whiting.

Table 7--Chemical requirements of whiting for the rubber industry. (Figures are percentages) (Wilson and Skinner, 1937, p. 31)

Co. Max.
in HCl
and MgO
SiO2 MgO Moisture
B     42-44 0.05-1.5         0.1-0.5
C   97.5 2     0.25 0.90   0.25
D 50   40   5.0     3.0 0.25

Table 8--Specifications for ceramic whiting. (Figures are percentages) (Wilson and Skinner, 1937, p. 31)

CaCO3 MgCO3 Fe2O3 SiO2 SO3
Class 1
Minimum 97 96        
Maximum     1 0.25 2.0 0.1
Class 2
Minimum 97 89        
Maximum     8 0.25 2.0 0.1

Chalk whiting for cold water paints and calcimine is governed by a number of factors (Bowles, 1942, p. 4), depending upon the use of the finished product. In general, particle size, shape, and distribution, texture, chemical reactivity, oil absorption, color, and specific gravity are the prime factors.

For putty, the chemical specifications are 95 percent calcium carbonate or higher, with impurities plus tinting compound not to exceed 5 percent. The various properties of the different types of putty call for a number of physical specifications of which fineness of grain size, freedom from grit, and oil absorption are the most important.

Chemically precipitated whiting and various finely ground natural whitings are used as fillers, to increase opacity, and to improve printing quality in paper. The only definite specification given (Bowles, 1942, p. 5) is that fineness of grain size is important.

Many other uses of whiting have been listed but specifications are so varied that in most cases the suitability of the whiting is best determined by submitting samples to the prospective customer.

Other Uses of Chalk

The following discussion of the uses of chalk has been adapted from Lamar and Willman (1938).

Ground chalk is used for dusting coal mines to prevent explosions. The chemical requirements are high calcium carbonate and low silica content. All the chalk must pass a 20-mesh sieve, and 50 percent must pass a 200-mesh sieve. A light-colored powder, free from grit, is desired.

Ground chalk is employed for asphalt filler. All must pass a no. 30 sieve, not less than 95 percent should pass a no. 80 sieve, and not less than 65 percent should pass a no. 200 sieve. A more finely ground filler is used with asphalt for other purposes.

Chalk may be used for agricultural limestone or "agstone" as it is more familiarly known. The neutralization of soil acids and acid clays, releasing of some plant food elements from some soil minerals, the supplying of nutrients for plant use in the form of calcium, the favoring of the growth of vegetables, the improving of the type of decay of organic matter in the soil, and the conversion of toxic aluminum compounds soluble under acid conditions to insoluble compounds are but a few of the functions performed by the addition of calcium carbonate to soil. The requirements for agricultural limestone are a calcium carbonate equivalent of at least 80 percent. The physical requirements (1946) are 25 percent passing 100 mesh and 95 percent passing 8 mesh.

Chalk may be used as a filler and conditioner in fertilizers. Weight is added to fertilizers by fillers and the caking of fertilizers is reduced by conditioners. If there is superphosphate present, the chalk neutralizes any "free" phosphoric acid present. The general chemical specification for fertilizer manufacture is a reasonably pure chalk. The general physical specification is a fineness of 20 to 80 mesh.

Chalk may be used in making mineral feeds for stock. The general chemical requirements in Kansas (personal communication, Kansas State Board of Agriculture, 1947) are a calcium carbonate content of 80 percent (20 percent calcium) and less than 0.03 percent fluorine. The general physical specification is fineness of 200 mesh or finer.

Fort Hays chalk has been used locally as building material. By selection of beds, blocks from pure white to buff color can be produced with a minimum of equipment. There are two primary (objections to using Fort Hays chalk as a building stone: (1) iron concretions cause staining and (2) the chalk has low tensile strength, so that blocks chip easily. Both these objections are overcome by cutting relatively small blocks. Thus all iron concretions can be discarded with a minimum loss and the small block will "case harden" more quickly. (Freshly cut limestone or chalk hardens on the surface from exposure to air). The small blocks make very attractive buildings and enormous tonnages of easily accessible chalk are available.

Chalk can be used in Portland cement. The general chemical specifications are less than 2 percent magnesium carbonate, less than 1 or 1.5 percent total sulfur, and less than 0.5 percent P2O5 (J. H. Griffith, Lonestar Cement Corp., personal communication, 1947). The general physical requirements are ability to pulverize easily and 100-mesh size. The tolerance of Fe2O3 in white Portland cement is very low. Basal Fort Hays is utilized for Portland cement at Superior, Nebraska, and at Boulder, Colorado. It was used also at Yocemento, Ellis County, Kansas.

Lime is made by burning limestone or chalk at a temperature which drives off the carbon dioxide. The technology of the manufacture of lime is dependent on the chemical and physical properties of the raw stone and the manner in which it is burned. Lime produced from the Fort Hays chalk meets all specifications listed below.

Chalk or limestone for nonhydraulic limes must contain more than 91 percent calcium carbonate, less than 6 percent magnesium carbonate, and less than 3 percent other constituents. For hydraulic limes, the carbonates must be between 91 and 97 percent with 3 to 9 percent other constituents. The physical requirements are clean dry fragments from 6 to 10 inches if burned in vertical kilns, and 0.5 to 1.5 inches if burned in rotary kilns.

Other uses of lime include building material, such as plaster, mortar, brick, and stucco; in many chemical processes; in the purification of water; and in the treatment of sewage.

Comparison with Other Chalks

In the United States, chalk also occurs in Alabama, Arkansas, Colorado, Iowa, Mississippi, Nebraska, South Dakota, Tennessee, Texas, and Wyoming. Except for the basal part of the Fort Hays, the lowest calcium carbonate content in the Fort Hays is 88 percent, the highest is 98.1 percent, averaging (excluding the base) 94.2 percent. The chalk in Alabama is reported (Bowles, 1942, p. 6) to have a maximum of 85 percent calcium carbonate. In Mississippi the best chalk is reported (Bowles, 1942) to contain only 70 to 84 percent total carbonate, the magnesium content usually being less than 1 percent. Bowles (1942) states that chalk in Arkansas contains as much as 93 percent calcium carbonate, and 3 to 12 percent magnesium carbonate. The Iowa chalk ranges from 86 to 95 percent total carbonates and is low in magnesium (Bowles, 1942). As far as is known the chalk in Iowa has not been developed commercially. The Nebraska chalk is in the Niobrara formation and has a calcium carbonate content ranging from 67 to 96 percent (Bowles, 1942), and 1.5 percent or less magnesium carbonate. As far as is known, the Niobrara chalk has not been developed commercially except for use in cement. The Texas chalk (Bowles, 1942) has 70 to 90 percent calcium carbonate and contains flint nodules. South Dakota chalk (Wilson and Skinner, 1937, p. 146) contains from 69 to 98 percent calcium carbonate, 1.5 to 5.3 percent clay, 0.0 to 4.0 percent free silica, and 0.56 to 7.00 percent ferric oxide. The chalk is similar to the deposits of the same formation in Nebraska and Kansas, but has a darker color due to the presence of carbonaceous matter. This latter characteristic may limit its use for whiting. The chalks of Tennessee and Wyoming do not occur extensively and according to Bowles (1942, p. 15) show little possibility of commercial development.

France and the United Kingdom have been the leading exporters of crude chalk to the United States. The chalk in France (Cayeaux, 1935, p. 38) contains 90 to 98 percent carbonates, usually less than 1 percent clay, 0.5 percent silica except when the chalk contains siliceous spicules, and 0.04 to 2.82 percent P2O3. The lower English chalk is the most impure, containing 88 to 94 percent calcium carbonate, and averaging 89 to 90 percent. The middle chalk contains 93 to 98 percent calcium carbonate. The purest English chalk is in the upper chalk which contains 95 to 99 percent calcium carbonate (Tarr, 1925, p. 258). The chalk from Europe is, on the average, whiter than the Fort Hays and has a slightly higher calcium carbonate content.


The data obtained from this study shows that, in general, the Fort Hays chalk can meet, or be processed to meet, the requirements for whiting in the paint, rubber, putty, and chemical industries. The study also shows that the Fort Hays chalk is generally uniform in its properties throughout the area of outcrop in Kansas.

In addition to quality and quantity of raw materials, the development of a new industry is governed by many economic factors such as distance from existing markets, development of new markets, and distribution of competitors. A whiting industry in Kansas would have all the necessary raw materials, including water. The existing markets and the distribution of competitors are such that the possibilities for such an industry in the near future would be entirely within reason. A detailed study of the physical properties of Fort Hays chalk, supplementing the data given in this report, is being planned by the State Geological Survey.

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Kansas Geological Survey, Geology
Placed on web Oct. 6, 2008; originally published Feb. 1949.
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