Vermiculite 226985 222851422 2008-07-01T12:38:47Z Vsmith 84417 /* See also */ rmv irrelevant {{Infobox mineral | name = Vermiculite | category = | boxwidth = | boxbgcolor = | image = VermiculiteUSGOV.jpg | caption = | formula = ([[Magnesium|Mg]][[Iron|Fe]],[[Aluminium|Al]])<sub>3</sub>([[Aluminium|Al]],[[Silicon|Si]])<sub>4</sub>[[Oxygen|O]]<sub>10</sub>([[Hydroxyl|OH]])<sub>2</sub>·4[[Hydrogen|H]]<sub>2</sub>[[Oxygen|O]] | color = Honey | habit = Clay, scaly, aggregate | system = [[Monoclinic]] | twinning = | cleavage = Perfect | fracture = Uneven | mohs = 2-3 | luster = Vitreous | refractive = Translucent | opticalprop = | birefringence = | pleochroism = None | streak = Pale yellow | gravity = 2.4-2.7 | melt = | fusibility = | diagnostic = | solubility = | diaphaneity = | other = }} '''Vermiculite''' is a natural [[mineral]] that expands with the application of [[heat]]. The expansion process is called [[exfoliation]] and it is routinely accomplished in purpose-designed commercial furnaces. Vermiculite is formed by [[hydration]] of certain [[mafic|basaltic minerals]]. Large commercial vermiculite mines currently exist in [[South Africa]], [[China]], [[Brazil]], the [[United States of America|USA]] and several other countries. ==Structure== Vermiculite is a 2:1 [[clay]], meaning it has 2 [[tetrahedral]] sheets for every one [[octahedral]] sheet. It is a limited expansion clay with a medium shrink-swell capacity. Vermiculite has a high [[cation exchange capacity]] at 100-150 [[meq]]/100[[Gram|g]]. Vermiculite clays are weathered [[Mica|micas]] in which the [[Potassium|K]]<sup>+</sup> ions between the [[molecular]] sheets are replaced by [[Magnesium|Mg]]<sup>2+</sup> and [[Iron|Fe]]<sup>2+</sup> cations. ==Commercial uses== *moulded shapes, bonded with [[sodium silicate]] for use in: **high-temperature insulation **refractory insulation **[[fireproofing]] of structural [[steel]] and [[pipe (material)|pipe]]s *[[soil conditioner]] *as loose-fill [[Thermal insulation|insulation]] *packing material, valued for its high absorbency *suitable as a [[substrate (biology)|substrate]] for various animals and/or [[incubation]] of eggs *lightweight aggregate for [[plaster]], proprietary [[concrete]] compounds, [[firestop]] mortar and cementitious spray [[fireproofing]] *as an additive to fireproof [[wallboard]] *component of the interior fill for [[firestop pillow]]s, along with [[graphite]] *carrier for dry handling and slow release of agricultural chemicals *soil additive for plants, together with [[perlite]] for potted plants *growing medium for [[hydroponics]]. *means to permit slow cooling of hot pieces in [[glassblowing]], [[lampwork]], [[steelwork]], and [[glass beadmaking]] *used in in-ground swimming pools to provide a smooth pool base *used in commercial [[hand warmer|handwarmers]] *used as a sterile medium for the incubation of reptile eggs *light-weight insulative concrete [http://sugarmtnfarm.com/blog/2007/09/float-my-concrete-boat.html] *used in AGA cookers as insulation *used in explosives storage as a blast mitigant ==Commercial manufacture of exfoliated vermiculite== [[Image:2005vermiculite.PNG|thumb|right|Vermiculite output in 2005]] In 2005, South Africa was the top producer of vermiculite with about 40% world share followed by the USA and China, reports the [[British Geological Survey]]. While some exfoliators focus on only a few of the possible applications, others can provide vermiculite products for all its applications. It is common for vermiculite exfoliators to also exfoliate perlite, as both are often sold together. To set up a new exfoliation process, it is possible to find expert consultants to advise in the design and construction of the desired facilities. Vermiculite exfoliators have an international trade association called ''The Vermiculite Association'' to represent the industry's interests and to exchange information.<ref name="tva">{{cite web|title=The Vermiculite Association | url=http://www.vermiculite.org/}}</ref> Many of its members also maintain memberships in ''The Perlite Institute''.<ref name="tpi">{{cite web | title=The Perlite Institute | url=http://www.perlite.org/}}</ref> ==Fireproofing== For many years, since the advent of the [[asbestos]] removal business, before which nearly everyone sold asbestos-based spray fireproofing, vendors could be cleanly categorised into users of MMMF (man-made-mineral-fibres), which included both [[rockwool]] and [[ceramic]] fibres, and [[cement]]itious sprays, whereby the binder was typically [[portland cement]] and the lightweight [[Aggregate (composite)|aggregate]] inside the [[plaster]] was vermiculite. For many years, makers of the cementitious products would point out the ill health effects that are possible from overexposure and lack of proper industrial [[hygiene]] procedures when working with MMMF. Vendors of the MMMF products would point out the possibility of asbestos contamination, particularly with US mined vermiculite ore. Ironically, both sides were defending against [[lawsuit]]s in the asbestos litigation and eventually stopped pointing out these particular weak spots about one another, which makes sense, since most affected [[manufacturer]]s are still in [[receivership]] as a means of dealing with the results of the asbestos litigation. One large [[United Kingdom|British]] manufacturer of asbestos products even had to discontinue selling anything to [[North America]] directly, having to rely on surrogate trading companies for sales to that continent now. {{Fact|date=November 2007}} ==Controversy over health risks== An article published in the [[Salt Lake Tribune]] on December 3, 2006 reported that vermiculite and Zonolite (a brand of insulation made from vermiculite) had been found to contain [[asbestos]], which had led to cancers such as those found in asbestos related cases. The article stated that there had been a "cover-up" by [[W. R. Grace and Company|W.R. Grace Company]] and others regarding the health risks associated with vermiculite and that several sites in the [[Salt Lake Valley]] had been remediated by the [[United States Environmental Protection Agency|EPA]] when they were shown to be contaminated with asbestos. W.R. Grace Company has vigorously denied these charges. W. R. Grace Company was the owner and operator of the former vermiculite mine in [[Libby, Montana]], which was the largest and oldest vermiculite mine in the United States. Although not all vermiculite contains asbestos, some products were made with vermiculite that contained asbestos until the early 1990s. Vermiculite mines throughout the world are now regularly tested for it and are supposed to sell products that contain no asbestos. The former vermiculite mine in Libby, Montana did have asbestos &mdash; in fact, it was found to have developed underground with and to be co-mingled with significant amounts of asbestos. Pure vermiculite does not contain asbestos and is non-toxic, but it can become contaminated over long periods if there is a presence of a secondary mineral called [[diopside]]. After millions of years of weatherization, the [[biotite]] turns into vermiculite and the diopside turns into asbestos. This appears to have happened to the vermiculite deposit at the Libby, Montana mine, and numerous people were unknowingly exposed to the harmful dust of vermiculite that contained asbestos. Unfortunately, the mine had been operating since the 1920s, and environmental and industrial controls were virtually non-existent until the mine was purchased by the W.R. Grace Company in 1963. Yet, knowing the potential for human health risks, the mining company still continued to operate there until 1990. Consequently, many of the former miners and residents of Libby had been affected and continue to suffer health problems. Over 200 people in the town died from asbestos-related disease due to contamination from vermiculite mining from nearby Zonolite Mountain, where soil samples were found to be loaded with fibrous [[tremolite]] (known to be a very toxic form of asbestos), and countless others there who insulated their homes with Zonolite have succumbed to asbestos-related diseases, most of whom never were employed in environments where asbestos was an issue.<ref name="cbc">{{cite news | title=Deadly dust | publisher=''[[CBC News]]'' | url=http://www.cbc.ca/national/news/deadly_dust/ | date=2003-02-07}}</ref> After a 1999 [[Seattle Post-Intelligencer]] story claimed that asbestos-related disease was common in the town, the [[United States Environmental Protection Agency|EPA]], in response to political pressure, made cleanup of the site a priority and called Libby the worst case of community-wide exposure to a toxic substance in U.S. history.<ref name="spinews">{{cite news | title=A town left to die: hundreds of miners and family members killed and sickened | publisher=''[[Seattle PI]]'' | date=1999-11-18 | url=http://seattlepi.nwsource.com/uncivilaction/}} </ref><ref name="epasuper">{{cite web | title=Libby Asbestos | publisher=[[United States Environmental Protection Agency]] | url=http://www.epa.gov/region8/superfund/libby/}}</ref> The EPA has spent $120 million in [[Superfund]] money on cleanup.<ref name="epasuper"/> In October 2006, W. R. Grace Company tried to appeal the fines levied on them from the EPA, but the Supreme Court rejected the appeal.<ref name="latimes">{{cite news | title=Firm Must Pay Asbestos Costs | publisher=LA Times | first=Sam Howe | last=Verhovek | date=2006-10-11 | url=http://www.latimes.com/news/nationworld/nation/la-na-grace11oct11,1,3194269.story?coll=la-headlines-nation}}</ref> The [[United States government]] is also pursuing criminal charges against several former executives and managers of the mine for allegedly disregarding and covering up health risks to employees.<ref name="latimes"/> They are also accused of obstructing the government's cleanup efforts and wire fraud. To date, according to the indictment, approximately 1,200 residents of the Libby area have been identified as suffering from some kind of asbestos-related abnormality.<ref name="usdoj">{{cite web | title=W.R. Grace and executives charged with fraud, obstruction of justice, and endangering Libby, Montana community | date=2005-02-07 | url=http://www.usdoj.gov/opa/pr/2005/February/05_enrd_048.htm}}</ref> The criminal proceedings are ongoing as of July 2007.<ref name="wpost">{{cite news | title=Asbestos Evidentiary Ruling Goes Against Grace | first=Carrie | last=Johnson | publisher=''[[The Washington Post]]'' | date=2007-07-13 | pages=D05 | url=http://www.washingtonpost.com/wp-dyn/content/article/2007/07/12/AR2007071201799.html}}</ref> Since the 1920s, vermiculite had been extracted from the Libby deposit under the commercial name Zonolite. The Zonolite brand was acquired by the W.R. Grace Company in 1963. Mining operations on the Libby site stopped in 1990 in response to asbestos contamination. While in operation, the Libby mine may have produced 80% of the world's supply of vermiculite.<ref name="epasuperbackg">{{cite web | title=Libby Site Background | publisher=[[United States Environmental Protection Agency]] | url=http://www.epa.gov/region8/superfund/libby/background.html}}</ref> The United States government estimates that vermiculite was used in more than 35 million homes but does not recommend its removal. Nevertheless, homes or structures containing vermiculite or vermiculite insulation dating from before the mid 1990s, and especially those known to contain the "Zonolite" brand, may contain asbestos, and therefore may be a health concern. ==See also== *[[Passive fire protection]] *[[Fireproofing]] *[[Firestop]] *[[Asbestos]] *[[Perlite]] *[[Sodium silicate]] *[[Plaster]] *[[List of minerals]] *[[Square foot gardening]] ==References== <references/> ==External links== *[http://murray.senate.gov/asbestos/asbestos-links.cfm United States Senator Patty Murray] *[http://www.ewg.org/issues/siteindex/issues.php?issueid=5002 Environmental Working Group] *[http://www.epa.gov/asbestos/ United States Environmental Protection Agency] *The Vermiculite Association [http://www.vermiculite.org/] *The Perlite Association [http://www.perlite.org/] *[http://www.scotusblog.com/movabletype/archives/W.R.GracePetition%28Apr.27%2C2006%29.pdf Petition for writ of certiorari to U.S. Supreme Court (April 27, 2006)] [[Category:Magnesium minerals]] [[Category:Iron minerals]] [[Category:Aluminium minerals]] [[Category:Hydroxide minerals]] [[Category:Phyllosilicates]] [[Category:Granular materials]] [[Category:Passive fire protection]] [[ar:فيرميكيوليت]] [[ca:Vermiculita]] [[cs:Vermikulit]] [[de:Vermiculit]] [[es:Vermiculita]] [[eu:Bermikulita]] [[fr:Vermiculite]] [[it:Vermiculite]] [[nl:Vermiculiet]] [[ja:バーミキュライト]] [[pt:Vermiculita]] [[sr:Вермикулит]] [[fi:Vermikuliitti]] [[sv:Vermikulit]] [[tr:Vermikülit]] [[zh:蛭石]]