UNITED STATES TARIFF COMMISSION GRAVEL, CRUDE Comment This summary covers crude gravel, which consists of loose rounded fragments of rock in a wide variety of sizes, usually larger than one-quarter inch in diameter. Commercial gravel usually does not contain pebbles larger than 24 to 3 inches in diameter. Gravel and send are of the same mineral composition, the distinction between them being in the size of the separate particles, the size of sand being much smaller than that of gravel. The principle uses of gravel in the United States are in building construction and in paving, and as railroad ballast. Gravel is produced throughout the United States. California, Texas, Ohio, Illinois, and Pennsylvania have usually accounted for nearly half the total output. The statistics on production include both production for sale (commercial production), and production by States, counties, municipalities, and other Government agencies and contractors for their own use (noncommercial production). The reported value per ton for commercial production is 50 to 100 percent higher than that reported for noncommercial output. Most of the noncommercial production consists of unprepared material-gravel which is not washed or graded-used for low-cost secondary roads. In years immediately preceding World War II commercial production accounted for a little less than one-half the total output; during the war it accounted for two-thirds to three-fourths of the total production and it was about 62 percent of the output in 1948. The total production of gravel in the United States increased steadily from 75 million tons, valued at 33 million dollars in 1933 to 197 million tons valued at 114 million dollars in 1942. The increase was due to the larger demand for paving, and, to a lesser extent, for building construction. Production declined somewhat during the war but has increased substantially in postwar years. mated output in 1948 was 185 million tons valued at 130 million dollars. Esti United States imports of gravel have been negligible, usually representing less than 0.1 percent of domestic consumption. Canada has been virtually the only source of imports, although small amounts have come intermittently from Mexico and the United Kingdom. Imports generally have supplemented the domestic supply to a limited extent in certain areas, particularly in the States bordering on Canada and Mexico. Imports in 1938 amounted to 89,000 tons, valued at $30,000 (foreign value). United States exports of gravel are not separately reported, but total exports of gravel and sand combined have seldom exceeded 50,000 tons annually. Most of these exports have gone to Canada. * KYANITE, SILLIMANITE, ANDALUSITE, AND DUMORTIERITE, CRUDE (PAR. 1719) Tariff Status Par. 1719. Kyanite and sillimanite, crude, or not advanced in value or condition, which were classified free of duty under the Tariff Act of 1922, are SUMMARIES OF TARIFF INFORMATION KYANITE, SILLIMANITE, ANDALUSITE, AND DUMORTIERITE, CRUDE (PAR. 1719) Trade Statistics Table 1. Kyanite, sillimanite, andalusite, and dumortierite, crude: 1/ Shipments of kyanite only; sillimanite, andalusite, and dumortierite are not produced in the United States on a commercial scale. Unlike imports, which are all crude, domestic shipments consist largely of processed (ground and/or calcined) maStatistics on United States production of crude kyanite are not separately 2/ Practically all crude kyanite, but includes some crude sillimanite starting with 1943. terial. reported. 3/ Includes Burma in 1937, and Pakistan in 1937-47. There were no imports from Pakistan in 1948, the first year for which statistics were reported for that country. 5/ Approximate. 6/ Preliminary. Not available. 7 Estimated to exceed 10,000 tons, valued at more than $300,000. Source: Production, official statistics of the U. S. Bureau of Mines, except as noted; imports, official statistics of the U. S. Department of Commerce. Note. Statistics on United States exports of crude kyanite and its three affiliated minerals in crude form are not separately reported, but exports are known to be very small, if any. UNITED STATES TARIFF COMMISSION KYANITE, SILLIMANITE, ANDALUSITE, AND DUMORTIERITE, CRUDE Comment Description and uses.-This summary covers the minerals kyanite, sillimanite, andalusite, and dumortierite, in their crude form or not advanced in value or condition by refining, grinding, or by other process of manufacture. 1/ All four minerals are aluminum silicates, having similar chemical compositions and similar uses, but differing in crystallization, specific gravity, and other physical properties. They are usually referred to in mineralogy as the sillimanite group of minerals. Of the group, kyanite is by far the most abundant, and it has long accounted for most of the United States production and for practically all of the imports. 2/ During World War II kyanite and sillimanite were considered strategic and critical materials, and imports, then virtually all from India, were placed under complete control of the War Production Board. When calcined or fired to high temperatures (over 1400° C.), the four minerals here considered lose their mineralogical identity and are converted into mullite, a highly refractory mineral, which is seldom found in nature. the four minerals owes its commercial value to this property. Each of Deposits of kyanite occur either as segregations of massive material or as deposits in which the kyanite crystals are widely disseminated through large masses of rock or schists. In foreign countries most of the kyanite is obtained from massive deposits, whereas in the United States the mineral is obtained from disseminated deposits. In general, massive deposits of kyanite are by far the most suitable for commercial exploitation because of the lower costs of mining such deposits and the superior quality and wider uses of the massive ore. Recovery of salable kyanite from massive deposits usually exceeds 75 percent of the ore, as mined, as compared to less than 15 percent in the case of most domestic (disseminated) deposits. Because of the wide dissemination of domestic kyanite throughout large masses of ore, it requires considerable processing before it can be used; this normally consists of grinding, tabling, flotation, magnetic separation, and calcination. On the other hand, the crude imported kyanite requires only calcination and grinding. Processed kyanite or mullite is used largely in the manufacture of so-called "super-duty" refractories / of the high-alumina type; it was the wartime requirements of such refractories which accounted for the strategic importance of this mineral. Kyanite is now listed as a material subject to stockpiling for national defense. Although kyanite refractories represent only a small percentage of the total tonnage of refractories used in the United States, they occupy an important position in that field because of their exceptional properties: their relatively high melting points; their low coefficient of expansion; and their resistance to loads at high temperatures, to thermal shock, and to the corrosive action of certain fluxing agents. Kyanite refractories are relatively expensive, but industry has found it profitable to use them for certain purposes. If ground, refined or otherwise advanced in value or condition, these minerals are dutiable under the provisions of par. 214, covering earthy or mineral substances, not specially provided for, not decorated (see separate summary under that paragraph). 2/ There is no record of crude andalusite and crude dumortierite ever having been imported. 3/ The term "refractories," as used hereafter, refers to products such as firebricks, refractory cements, etc., made from heat-resisting materials. In the case of kyanite refractories, the term refers to refractory products made from kyanite even though it has been changed to "mullite" by calcination preparatory to SUMMARIES OF TARIFF INFORMATION KYANITE, SILLIMANITE, ANDALUSITE, AND DUMORTIERITE, CRUDE Kyanite refractories are made in the form of prefabricated and burned bricks and shapes, or in the form of cements, mortars, plastics, and ramming mixtures; 1/ the bricks and shapes account for about two-thirds of all kyanite used by the domestic refractory industry. Most of the crude kyanite used in bricks and shapes is imported; for this use the imported massive kyanite is superior to the domestic product because it is recoverable, after calcination, in coarse, dense grain sizes (one-quarter inch to 35 mesh) highly essential to the manufacture of such refractories. In some instances, the relatively fine-grained (35 mesh or smaller) domestic product is blended with the coarser calcined imported kyanite in the production of refractory brick and shapes. For use in refractory cements, etc., the domestic kyanite is satisfactory and such uses, requiring a relatively fine-grained material, account for the major part of the United States consumption of the domestic product. About 90 percent of all kyanite refractories go into furnaces operated by the metallurgical and glass industries, the approximate division between the two being about 55 percent metallurgical and 45 percent glass. The remaining 10 percent finds miscellaneous applications in the ceramic and chemical industries. In the metallurgical industry the chief use of kyanite refractories is in electric furnaces, largely the induction type used for melting brasses and bronzes. In the glass industry these refractories are used chiefly in the construction of continuous glass furnaces, especially in that part known as the superstructure. Increasing amcunts of kyanite, chiefly domestic, are being used as an ingredient of glass; for this use a fine-grained, iron-free material is required and the method of processing the domestic ore contributes to its suitability for that purpose. Relatively small quantities of kyanite are also used in certain types of ceramic whiteware, such as electrical and chemical porcelains, and pyrometer tubes. There are substitutes for practically every application in which kyanite refractories are employed, but efficiency would be greatly lowered in many cases through the use of the substitutes and in some instances they themselves are difficult to obtain or are relatively expensive. Among these substitute materials are the following refractories, as designated by their composition--fireclay (particularly the super-duty type), silica, high alumina, fused alumina, magnesite, chrome, magnesia-alumina, and fused alumina-silicate. In electric furnaces used for melting brasses and bronzes, which are the chief outlets for kyanite refractories in the metallurgical field, fireclay refractories can be satisfactorily used only in those furnaces melting yellow bress. In furnaces used for melting the higher-meltingpoint alloys (brasses and bronzes) high in copper, kyanite refractories are most desirable. Fused alumina and magnesia-alumina refractories can be satisfactorily used in place of kyanite refractories in melting these high-melting-point alloys, but they are difficult to install and their production requires the use of considerable electric power. In certain parts of continuous glass furnaces, where kyanite refractories are used, a few substitutes, such as kaolin, silica, and high-alumina refractories, and those made of electrically fused (artificial) mullite, can be used; however, the latter is very expensive and the other three may or may not cause some lowering of efficiency depending on the point of use. As a general rule, industry is reluctant to shift from the use of kyanite refractories, once they have proved, by performance, their suitability for certain uses. 1 Kyanite refractories, if imported in the form of brick and shapes, are dutiable under par. 201(a) covering firebrick, not specially provided for (see separate Summary under that paragraph); if imported in the forms of cements, etc., kyanite refractories are dutiable under par. 205(d), covering cement, not specially provided for (see separate summary). Imports of kyanite refractories have been negligible. UNITED STATES TARIFF COMMISSION KYANITE, SILLIMANITE, ANDALUSITE, AND DUMORTIERITE, CRUDE United States production.-The United States kyanite industry is a relatively new one; it was still in an early stage of development as recently as the late 1930's. In those years, production of kyanite is estimated to have averaged, annually, less than 3,000 short tons, valued at less than $65,000. Under the inpetus of wartime demands, and an increasing realization of the excellence of kyanite refractories, shipments by United States producers advanced to 9,500 tons, valued at $240,000, in 1943. Although separate statistics on shipments of domestic kyanite were discontinued after 1943, because of their confidential nature, shipments in recent years have undoubtedly exceeded those of 1943; in 1946-48, they are estimated to have averaged, annually, over 10,000 short tons, valued at more than $300,000. Virtually all of the many known deposits of domestic kyanite are located in the Southern-Appalachian area, but only a very few of them are suitable for commercial exploitation. Most of the shipments are now accounted for by two concerns, one in south-central Virginia and the other in north-central South Carolina, the latter being a relatively new undertaking. kyanite is also produced in Georgia and California, but most of the output of these States is mined by producers for their own use. Until several years ago, North Carolina had been fairly important as a source of domestic kyanite. Some United States production of the other minerals of the so-called "sillimanite group" has been limited to small amounts of andalusite and dumortierite of which very little, if any, has been sold in the open market. Until recently, a large manufacturer of electrical porcelain had long mined andalusite in California and dumortierite in Nevada for his own use, but in 1947 the two mines were not operated and in the latter part of that year they were sold. One other concern operates a small andalusite mine in Nevada for its own use in the manufacture of chinaware. Although many occurrences of sillimanite heve been reported in the United States none of them has so far been operated on a commercial scale. United States imports.-Statistics on United States imports of crude kyanite and the other minerals here considered were not separately reported until 1937, but imports before then, virtually all from India, are believed to have been relatively small compared with those in later years. Imports since 1936, consisting very largely of crude kyanite, have fluctuated considerably from year to year. The annual average in 1938-39 of 3,700 tons was about one-half of the quantity imported in either 1937 or 1940. On account of wartime demand, imports increased to 14,000 tons, valued at $175,000, in 1941. In December of that year, the importation and use of imported Indian kyanite were placed under government control. Despite strenuous efforts to promote imports of kyanite during the war, 1945 was the only year during the period 1942-47 in which imports exceeded those of 1941. In 1946 and 1947 imports averaged 11,800 tons, valued at $140,000, annually, or considerably less than in 1941, but in 1948 they were the highest on record, amounting to 17,000 tons, valued at $259,000. Deposits of high-grade massive kyanite were discovered in India in 1924 and, until recently, thet country had been the world's leading source of supply of the mineral; in no year from 1937 to 1946 (except for 1938) did India supply less than 89 percent of the total United States imports, in quantity. Of the total tonnage imported in 1937-39, India supplied 92 percent, and in 1940-46 its share was 96 percent. In 1947 the proportion of United States imports supplied by India declined greatly, partly from unsettled conditions in India, partly from increased imports of kyanite from Kenya, British East Africa, and partly from increased imports of sillimanite from Australia, virtually the sole source of imports of that mineral (see table 1). High-grade deposits of massive kyanite were discovered in Kenya in 1940 and since that time the country has greatly increased its production and exports. In 1947 Kenya supplied more than one-half of the total quantity and value of United States imports while India supplied about one-third. In 1948 Kenya was the principal source of imports on the basis of quantity and India was the principal source on the basis of value. Although the average unit foreign value of inports from Kenya is lower than that of imports from India (see table 1), the quality |