Talc, New York

Stille WT, Tabershaw IR The mortality experience of upstate New York talc workers. J Occup Med 24 480M84, 1982... 

New York talc - This is generally considered synonymous with tremolitic talc as described above. 

Talc of metasedimentary origin is formed by hydrothermal alteration of a dolomitic host rock by a silica-containing fluid. This type of deposit is typical of Montana and AustraUa. It is usually quite pure with talc content of 90 to 98% and often very white as well. Dolomite [17069-72-6], CaMg(C02)2, is the most common accessory mineral. The fourth type is of metamorphic origin, where a siUcaceous dolostone is first converted to tremolite [14567-73-8] or actinohte [13768-00-8] and then partially converted to talc. The Balmat, New York, and Death Valley, California, deposits are of this type. Tremolite, dolomite, and serpentine are common accessory minerals. This type of talc deposit has a variable talc content (30—80%), but is usually white and often commercially exploited because of the properties of its accessory minerals rather than the talc. 

According to statistics collected by the U.S. Geological Survey (3), U.S. production of cmde talc in 1995 was 1,050,000 metric tons. Montana, Texas, Vermont, and New York were the principal producing U.S. states. Worldwide production was estimated to be 5,845,000 t. China, having 2,400,000 t, was the largest producer in the world after China and the United States, Finland, India, Brazil, France, Italy, and Canada are the next principal producers. World production of talc in 1994 is Hsted in Table 1. 

The mills in the western United States, in which generally are ground softer talcs than those of New York, have simple flow sheets. Single-stage crushing is employed, and the talc is merely ground in Raymond roller mills in closed circuit with air separators. 

Kleinfeld M, Messite J, Kooyman O, Zaki MH Mortality among talc miners and millers in New York State. Arch Environ Health 14 663-667, 1967... 

Radosta JA, Trivedi NC (1987) Talc. In Katz HS, MUewski JV (ed) Handbook of fillers for plastics. Van Nostrand, New York, p216... 

It is found chiefly in the metamorphic rocks, often those of a more basic type due to the alteration of the minerals above mentioned. Some localities are the Austrian Tyrol, the St. Gotthard district of Switzerland, Bavaria and Cornwall, England. In Canada, talc is found in Brome County, Quebec and Hastings County, Ontario, In tire United States, well-known localities are to be found in Vermont, New Hampshire, Massachusetts, Rhode Island, New York, Pennsylvania. Maryland, and North Carolina,... 

Talc fibers may be present in some talcs, especially if the talcs contain anthophyllite or tremolite asbestos and a metamorphosis or transition to talc has taken place. The transition is sometimes incomplete as in talcs from the Gouveneur district of upper New York State. If talc fibers are present, further testing as described below will be necessary. 

Tremolite-actinolite is present in or around some deposits of chrysotile asbestos. However, levels of amphibole asbestos in commercial chrysotile were not reported. Tremolite is a contaminant in talc from New York and California, but the extent and fibrosity of the tremolite is unclear (DOT 1980 Wagner et al. 1982c American Thoracic Society 1990). The tremolite in some talc Ifom Califomia has been described as flake-like and that from New York as having fine fibers (Wagner et al. 1982a). Some tremolite in the chrysotile Ifom Quebec has been described as having coarse fibers. A British survey of talc powders used for various purposes identified 3 out of 24 samples as containing tremolite. Ten of 20 samples of cosmetic talc purchased in New York City between 1971 and 1975 contained 1-14% (w/w) of fibrous tremolite and... 

Fitzgerald EF, Stark AD, Viarma N, et al. 1991. Exposure to asbestiform minerals and radiographic chest abnormalities in a talc mining region of upstate New York. Arch Environ Health 46 151-154. 

Fig. 16.3 Layered silicate structures (a) talc, Mgj(OH)3(SLO o) (b) muscovite (a mica) KAI (OH) (Si)AIO i,). IMne (I) Electroneutrality is maintained by balance of K(l). Mg(ll). AUMI). and Si(IV). (2) The repealing layers in muscovite are bound together by the K cations.) [From Adams. D. M. Inorfianic Solic/s-. Wiley New York. 1974. Reproduced with permission. ...

The composition of talc varies depending on its source. The most important factor is the amount of tremolite present. In the USA, for instance, Montana talcs are considered to be asbestos and tremolite free. The California plate-like talcs contain minor amounts of tremolite (less than 3%), whereas hard talcs contain between 5 to 25% tremolite. Some industrial talcs mined in upper New York State contain 25 to 50% tremolite. The other important component in its composition is water which is chemically combined in the magnesium oxide or brucite layer. Figure 2.62 shows the molecular structure of talc. Talc may lose this water only on... 

Back filling n. A solution composed of varying amounts of cornstarch, China clay, talc, and tallow that is applied to the back side of low-grade, low-cost cloth to change its hand, improve its appearance, and increase its weight. Complete textile glossary. Celanese acetate EEC, New York, 2000. 

Morawetz H (1995) Polymers the origins and growth of a science. Dover Publications, New York Mueller CD, Nazarenko S, Ebeling T, Schuman TL, Hiltner A, Baer E (1997) Novel structures by microlayer coextrusion - Talc filled PP, PC/SAN and HDPE/LLDPE. Polymer Eng. Sci 37 355-362. DOI 10.1002/pen. 11678... 

Patton (1973e) Patton, T.C. Magnesium Silicate (Talc) Pigment Handbook 1 Patton, T.C. (ed.) John Wiley, New York (1973) 233-242... 

TALC. 3Mg0-4Si02-H20. Talc is a hydrous magnesium silicate, with the composition 63.4% SiOj, 31.9% MgO and 4.7% HjO when found in pure form. It is an extremely soft mineral with a Mohs hardness of 1, has a platy structure and it is naturally hydro-phobic. Talc occurs as a relatively pure massive mineral in Montana, Australia and China. Elsewhere it occurs in conjunction with magnesite (Vermont, Quebec, Ontario and Finland), with tremoUte and serpentine in New York and with chlorite in France and Austria. In many ceramic applications, the presence of non-talc minerals such as chlorite and tremolite are beneficial. 

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