Serpentine occurrence

Clnysotile belongs to the serpentine group of minerals, v arieties of which are found in most of the important mountain ranges and precambrian shields (8). Only a small part of these serpentine occurrences are in the asbestiform clnysotile variety. Chrysotile fibers are found as veins in serpentines or related minerals in serpentinized ultramafic rocks and in serpentinized dolomitic marbles (9). It has been suggested that the ultrabasic rocks (forsterite, Mg-rich pyroxenes, and ampliiboles) are first attacked in an hydrothermal process and transformed in serpentines in a later hydrothermal event, the serpentines are partially redissolved and crystallized as chrysotile fibers (9). (Heady, the genesis of each chrysotile deposit must have involved specific features related to the composition of the precursor minerals, the stress and defomiations in the host matrix, the water content, the temperature cycles, etc. Nonetheless, it is generally observed that the chemical composition of the fibrous phase is closely related to that of the surrounding rock matrix (9). 

The fibrous forms of amphiboles, and serpentines, in addition to occurring in aggregates amenable to mining, are widespread as minor constiments of many rocks. The fibers are also widely distributed throughout the soils and waters of the world. These occurrences, together with the many long-term uses for asbestos society has devised, ensure that the ubiquitous presence of asbestos in our environment. 

Silicate minerals that usually occur as spherulitic aggregates of fibers have formed as a result of the alteration of the many minerals subsumed within the category of biopyriboles. Alteration of the micas under hydrothermal conditions produces compositional variants on recrystallization such as hydrous muscovite. Some of these samples have been labeled asbestiform, probably because they are found in veins that criss-cross rock masses. Fibrous micaceous minerals also occur as discrete disseminated particles, although few detailed analyses of crystallites from the disperse occurrences have been made. Fibrous mica found in veins usually grades (composition-ally) into members of the serpentine mineral group, the clays or the chlorites. 

Ross, M. (1981). The geologic occurrences and health hazards of amphibole and serpentine asbestos, pp. 279-324. In Veblen, D. R., ed. Amphiboles Petrology and Experimental Phase Relations. Reviews in Mineralogy, 9B. Min. Soc. America, Washington, DC. 

Rocks consisting essentially of olivine alone are known as dunites, the name coming from the occurrence of this rock in the Dun mountains of New Zealand. In the United States, this mineral is found in North Carolina, South Carolina, and Georgia, where corundum is associated wtith the dunite in commercial quantities. The olivine of peridotites alters readily to the mineral serpentine, often to such an extent that the rock itself is called a serpentine. As mentioned above, the pendotites may contain chromite or other valuable minerals, often to such an extent that they may be commercially exploited, for nickel, platinum, and precious garneL... 

Chrysotile deposits of economic value are found in Quebec, Canada, in the former U.S.S.R., and in South Africa. Minor occurrences are found in the United States in Vermont, New York, New Jersey, and Arizona. Verd antique marble (serpentine marble) is quarried extensively near West Rutland, Vermont. 

Titanium-bearing chondrodite appears to be much less common than is titanoclinohumite in either ophiolitic or xenolithic occurrences. It has been reported from meta-gabbroic dikelets in serpentinized ophiolite of Liguria (Italy) by... 

The culture of hairy roots is an attractive alternative to the use of undifferentiated cell cultures to obtain secondary metabolites, since roots grow rapidly in hormone-free liquid medium, they are genetically stable and are differentiated cells potentially able to produce more secondary metabolites than undifferentiated cells. Hairy root cultures produce a broad spectrum of TIAs. Production of ajmalicine, serpentine, and catharanthine has been repeatedly reported by different authors, sometimes with levels superior to nontransformed root cultures (around 0.2-0A% DW) [49,50]. Production of vindoline has been surprisingly detected in hairy roots, in levels which are not so low (0.04-0.08% DW) [49, 51]. Very recent work with C. roseus hairy roots include elicitation treatments, overexpression of TIA genes, and regulatory transcription factors, but although vindoline is reported in some cases, the occurrence of anticancer TIAs was never reported, and vindoline levels were always below 0.08% DW [52-55]. 

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