Tremolite actinolite

Retrograde metamorphic processes, linked to hydrothermal fluid circulation, finally produced a new mineral assemblage constituted mainly by tremolite-actinolite> epidote + chlorite + quartz + sericite + titanite + hematite. The amphibole appears as green fibrous crystals over clinopyroxene and other anhydrous minerals. 

Hornblendes, one series of Ca—Al-containing amphiboles (see Table 2.4), are particularly common minerals. Their chemical and physical properties resemble those of the tremolite-actinolite series, but hornblendes generally do not occur in a fibrous habit. They contain Al" in both tetrahedral and octahedral sites, whereas the asbestos varieties of amphibole contain little Al. This observation suggests that small variations in composition may be one of the important factors in generation of fibrous amphiboles. 

Over the past several decades six different silicate minerals have been mined as asbestos and processed for industrial and commercial applications. The most commonly encountered asbestos mineral today is chrysotile. The five other minerals are tremolite, actinolite, anthophyllite, grunerite, and rie-beckite. All five are members of the amphibole group of minerals, and each can occur as chunky, acicular, or equant crystals, as well as in fibrous form. When found as fine fibrous aggregates, in quantities appropriate for mining, they are usually distinguished as a special variety—for example, tremolite-asbestos. 

Calcic amphiboles of the tremolite-actinolite series show complex variations of Fe2+ ordering. A common Fe2+ site enrichment pattern is Ml > M3 > M2 M4. In F -bearing amphiboles, however, Fe2+ are relatively enriched in the M2 site due to F ion avoidance described later ( 6.7.7). 

If asbestos is present and the sample is not a talc sample, it is most likely to be chrysotile since about 90% or more of the asbestos used in American industry is chrysotile. If the sample is taken from a shipyard, there is a high probability that it will be amosite asbestos. If asbestos is found in a talc sample, it is likely to be anthophyllite or tremolite-actinolite or an asbestos intermediate fiber chrysotile is a possibility, however. If the sample is insulation, expect a variety of fibers. 

Asbestos is the name given to a group of six different fibrous minerals (amosite, chrysotile, crocidolite, and the fibrous varieties of tremolite, actinolite, and anthophyllite) that occur naturally in the environment. One of these, namely chrysotile, belongs to the serpentine family of minerals, while all of the others belong to the amphibole family. All forms of asbestos are hazardous, and all can cause cancer, but amphibole forms of asbestos are considered to be somewhat more... 

Characteristic Asbestos Amosite Chrysotile Tremolite Actinolite Anthophyllite Crocidolite... 

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... 

Amandus HE, Althouse R, Morgan WKC, et al. 1987. The morbidity and mortality of vermiculite miners and millers exposed to tremolite-actinolite Part III. Radiographic findings. Am J Ind Med 11 27-37. 

Samples of the fibrous amphibole in the Libby vermiculite ore, popularly referred to as tremolite asbestos, were recently analyzed by U.S. Geological Survey scientists. On the basis of variable chemical composition, several different mineral names were assigned to the samples winchite, richterite, tremolite, actinolite, ferro-edenite, and magnesio-arfvedsonite. All of these are classified as amphibole minerals. 

For regulatory purposes, the Occupational Safety and Health Administration (OSHA 1992) concluded that there was insufficient evidence that nonasbestiform forms of tremolite, actinolite, and anthophyllite will produce adverse health effects of the same type and severity produced by chronic exposure to amphibole asbestos (OSHA 1992 Vu 1993). Nevertheless, the reader should be aware that repeated exposure to excessive amounts of insoluble dusts of any type can cause adverse health effects including interstitial pulmonary fibrosis (ACGIH 1996 OSHA 1992). 

In an early EPA-supported study, -21% to 26% of the weight of raw ore samples and 0.3% to 7% of the weight of vermiculite concentrate samples from Libby were accounted for by asbestiform amphibole identified as tremolite-actinolite (Atkinson et al. 1982). In a 1984 study of samples from Libby, Montana, conducted by W.R. Grace, asbestiform amphibole percentage by weight varied from 3.5% to 6.4% in raw ore and from 0.4% to 1.0% in the concentrate (cited in Amandus et al. 1987a). 

Verkouteren JR, Wylie AG. 2000. The tremolite-actinolite-ferro-actinolite series systematic relationships among cell parameters, composition, optical properties, and habit, and evidence of discontinuities. Am Mineral 85 1239-1254. 

SYNONYMS Chrysotile, amosite, crocidolite, tremolite, anthophyllite, actinolite, tremolite, actinolite, serpentine chrysotile, white asbestos, blue asbestos. 

Asbestos is the name given to a group of naturally occurring silicates, chrysotile, amosite, and crocidolite, and the asbestiform types of tremolite, actinolite, and antho-phylite. Exposure to asbestos is a well-documented cause of pulmonary and pleural fibrosis, iung cancer, and mesothelioma, illnesses that may appear many years after exposure. 

Asbestos (anthophyllite, tremolite-actinolite, amosite, crocidolite, chrysotile), nonasbestos fibres Analytical electron microscopy of 50 lung tissue samples from Matsubase, where pleural plaques are endemic Number of asbestos bodies and fibres/ 5 g wet lung tissue frequency of pleural plaques size parameter of fibres Dy mineral type Anthophyllite (mean length 25.1 n, mean diameter 0.84 (un) might be responsible for the increased prevalence of pleural plaques in Matsubase. The aspect ratio of anthophyllite (mean = 38.7) was lower than that of amosite (mean = 81.8), which, as reported hy Murai and Kitagawa (1992), was found predominantly in cases of pleural mesothelioma. Murai et al. (1997) Differences in fibre size may be related to the strength of the carcinogenicity to the pleura. 

All suspect materials should be analyzed for asbestos content by a reputable laboratory (in the USA, those certified by the American Industrial Hygiene Association). Museum personnel should not conduct these analyses themselves even if they know how and have the proper facilities. (It should be noted that in the USA, the OSHA Asbestos Standard does not differentiate between blue, brown, and white asbestos, applying to all three a Permissible Exposure Level of 0.2 fibers per cubic centimeter. If the new OSHA Standard s partial stay is lifted, tremolite, actinolite, and anthophyllite will be similarly regulated.)... 

Mineralogy Asbestos is a name for a set of naturally fibrous silicate minerals. Asbestos minerals have been used because of their high tensile strength, high heat resistance, resistance to chemical attack, and ability to be woven into cloth (Dupres et al. 1984). These properties vary by asbestos fiber type. There are six accepted types of asbestos fibers namely, chrysotile, amosite, crocidolite, antho-phyllite, tremolite, and actinolite. These fibers can be separated into two broad mineralogical groups chrysotile or amphiboles, the latter including amosite, crocidolite, tremolite, actinolite, and anthophyllite. Table 2.1.6 lists the diseases caused by asbestos. While Table 2.1.6 is correct in broad outline, there are considerable discrepancies in the abil-... 

According to local geology, non-industrially used tremolite-actinolite asbestos fibers are naturally present in the soils and eventually used for domestic applications in some areas of the world. Migrants originating from these countries may undergo further exposure to industrial asbestos in the host country. In this context, clarification of the fiber type(s) involved using electron microscopy analysis is helpful to asses the contribution of environmental/domestic and occupational exposures (Dumortier et al. 2001c). 

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