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Vermiculite Insulation particles (C) Daniel FriedmanVermiculite History & Properties
Vermiculite discovery, mining history, properties

Vermiculite history & properties:

This article describes the early history of discovery, description & mining of vermiculite and we describe the properties of vermiculite that have formed the basis of its widespread uses in many different products & applications, from fireproofing sprays to potting soil.

In this article series we also give the history of the Libby vermiculite mine, its purchase by WR Grace Corporation, the asbestos-related bankruptcy filing, asbestos abatement cost claims & filings & the current ZAI settlement trust that may assist building tenants or owners with vermiculite removal costs.

We list other, including current producers of vermiculite insulation. This document assists building buyers, owners or inspectors who need to identify asbestos materials (or probable-asbestos) in buildings by simple visual inspection.

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

Vermiculite & Vermiculite Insulation History & Properties

Vermiculite in a 1940s Tennessee home (C) D Friedman D Phillips Watch out: vermiculite from some sources contains asbestos and can be an asbestos dust hazard in buildings. Details about the asbestos content in some vermiculite insulation products is found in this article.

[Click to enlarge any image]

Vermiculite is a mineral (hydrated laminar magnesium-aluminum-iron silicates or hydrated phlogopite or biotite mica) from the phyllosilicate group. Vermiculite looks somewhat like mica in that it includes shiny flat plates of material that can be separated.

Vermiculite has a wide range of uses in industry, construction, packaging, insulation, packaging, even animal feed.

Building owners of older structures that had little or no attic insulation are most-often familiar with vermiculite that was poured into attic floors as a loose-fill insulating product. In some buildings vermiculite may also have been blown into previously-uninsulated wall cavities. See VERMICULITE LOOSE FILL Attic Insulation May Go Unrecognized as a Potential Hazard

In addition to its use as an insulation product and in construction as a masonry fill, a cavity fill, & in concrete blocks, vermiculite is added to soils in horticultural applications and to cement to make a lightweight concrete swimming pool base.

In contemporary building construction (2016) vermiculite is used in lightweight concrete and it has been widely used in spray-applied fireproofing. Spray-on fireproofing takes advantage of the light-weight and fireproof properties of vermiculite.

Older spray fireproofing that also used vermiculite may have employed Libby Amphibole Asbestos (LAA) from the Libby Montana mine: a vermiculite source that contained asbestos in several forms that we list later in this article. After 1991 spray-applied fireproofing that uses vermiculite would not be expected to use Libby-Montana vermiculite, so it would not be expected to be contaminated with asbestos. Pure vermiculite would not contain asbestos.

Vermiculite is also used in special applications such as industrial filters [17], in ceramics (ground & exfoliated, bonded with calcium silicate to form an unfired insulating layer), as a heat resistant component in brake linings (Yun 2010) and even as a treatment for oil-contaminated waters (Mysore 2005) and as a dessicant 1942).

And as we illustrate below, vermiculite insulation can show up as an insulating layer in many products such as a ceiling light fixture.

History of the Discovery of Vermiculite, Vermiculite Mining & Uses from 1824

Vermiculite insulation large 1.5cm particles (C) Daniel FriedmanUses of vermiculite were explored as early as 1824 by Webb, appearing the very next year in Robinson's catalog of American minerals. (Robinson 1825)

Vermiculite was first mined commercially in North America in Colorado in 1915, as we cite below. Just five years later Hermann, a physicist described vermiculite (Hermann 1828) and Ten years after Webb, Bunsen, a German physicist, described vermiculite. (Bunsen 1834).

Three years later Del Rio described the crystals formed in vermiculite when it was heated (Del Rio 1837).

Vermiculite was later cited among the minerals of Japan in 1904 (Wadi 1904).

The most infamous and probably highest-production of vermiculite in North America was by the Zonolite company who mined vermiculite at the Libby Montana vermiculite mine between 1923 and 1990. Still larger is the Phalaborwa Vermiculite (PV) mine in South Africa. The Phalaborwa vermiculite mine was begun by Or Hans Merensky in 1946.

Research on the Early History of Vermiculite & Vermiculite Mining

Properties of Vermiculite Insluation

Chinese vermiculite from the Leijie Trade Co., Ltd. www.hbeijie.comBecause this mineral expands to many times its original volume when it is heated, processed vermiculite produces a lightweight material with insulating and other useful properties. Vermiculite is also fireproof (non-combustible), pH neutral, and is non-reactive to any but the strongest acids.

Vermiculite is also compressible.

These properties have given vermiculite a wide range of uses in industry, construction, packaging, insulation, packaging, even animal feed.

At HOW TO IDENTIFY VERMICULITE INSULATION we include photographs of a variety of sizes and shapesa of vermiculite insulation fragments or particles.

Vermiculite insulation is comprised of small light-weight fragments, typically between 1/8 and 1/4" in rough diameter, silver-colored to tan or light brown in color, with a bulk densaity of 4 to 10 pounds per cubic foot.

Vermiculite insluation itself does not burn: it is non-combustible, though contaminants and debris, if mixed with any insulating material at enough volume, might burn. When wet, vermiculite can hold a lot of water, as much as 220-325% by weight, and as much as 20-50% by volume.

This water-holding property is probably a reason we find vermiculite used in potting soil preparations and it may explain in part why vermiculte can be electrically conductive.

Schunldler Co. lists 9 elements typically found in vermiculite, including these principal ones when ranked as percent by weight: SiO2, Al2O3, MgO, Fe2O3, and H2O (water)

Electrical Conductivity of Vermiculite

I was inspecting a home in Providence, built in 1918 and the attic has vermiculite. As I was testing knob and tube wiring in the vermiculite to confirm it was live, I sort of lost my balance a little and my voltage detector went off far from the source of the electric wiring. I stopped and searched again, no wiring near where I was, so I began testing random locations and the voltage tester was picking up current as far away as 2 feet from wires.

It seems the Vermiculite was extending the EMF field far from the wiring. I showed it to an electrician who happened to be there and he was dumbfounded. I went over to some rock wool and tried it, and got nothing, then back to vermiculite and got a hit again.
I just wonder if you ever heard of this, or anyone in your circles ever heard of it? - David Grudzinski 2016/08/10

Reply:

Interesting. I did a quick research and report on it below.

Indeed there are some surprising things that will conduct an electrical field.
In a stand-alone garage I found that wet plywood roof sheathing was acting like a capacitor and conducting and increasing current that I could measure by touching between a roofing nail protruding through the plywood and a ground source.

Physical properties of vermiculite including its electrical conductivity:

More scholarly articles about the Properties of Vermiculite & its Electrical Conductivity

Vermiculite Insulation particles (C) Daniel FriedmanNoborio (2001) has one of the most-cited articles on thisa. He found that the water content in vermiculite was a factor in its conductivity. Liu (2006) also looks at the conductivity of vermiculite.

I also found (researching your question) that EMF has been used to test the water content of soil, a related observation. These articles (cited below) discuss the phenomenon, but I've not come across it in home inspection or construction discussions. I suspect that besides moisture content, the FeO2 and component and similar components may affect the conductivity.

What should I do if I have vermiculite insulation in my building ?

Quoting & paraphrasing or elaborating further from the U.S. EPA information on Vermiculite[5]:

You should assume that the vermiculite insulation contains asbestos and it should not be disturbed. Particularly, do not stir up nor spread dust from this product.! Any disturbance could potentially release asbestos fibers into the air. If you absolutely have to go in your attic and it contains vermiculite insulation, you should limit the number of trips you make and shorten the length of those trips in order to help limit your potential exposure.

We and the US EPA recommend that you:

For more details about the inspection and detection of concerns with fiberglass building insulation, see:

U.S. & Canadian Guides to Asbestos-Hazards in Vermiculite Insulation now found at

How Vermiculite Attic Insulation Becomes Airborne

Any airborne dust particles can be a respiratory irritant, but the hazard level is likely to be increased if the dust contains insect or rodent materials and of course also if it contains asbestos as is present in some vermiculite insulation installations. Particularly where loose fill vermiculite insulation remains exposed in an attic, such as in the attic floor, the following act ivies are likely to cause dust from this product to become airborne.

You can reduce these dust risks by installing a plywood floor over the tops of the floor joists (ceiling joists of the rooms below), by installing fiberglass batts on top of the vermiculite, or by spraying an acrylic encapsulant on the exposed surface of the vermiculite in the attic.

Watch out: spray-coating the upper surface of an attic insulation material installed in the floor risks creating a vapor barrier on the wrong side (the cold side) of the structure, trapping moisture and leading to condensation or even mold troubles.

Question: is .0004% of asbestos ok to be working in and preparing food in?

I work in a school in mt, and 2 years ago this substance was removed from two rooms in the school, one which is right by the kitchen i work in. well 2 days ago i found this substance on top the the cupboards and everywhere else, and can see that it is falling from the ceiling. Very concerned because i have a fan blowing in there, and there was asbestos in the school when they came and had it cleaned. my question to you is, is .0004% of asbestos ok to be working in and preparing food in?

i truly found this site excellent, it answered alot except that one question. thank you - Amy Swanson 9/2/11

Reply:

Thanks for tine nice note Amy.

A proper asbestos cleanup project, especially in a school, should have included post-cleanup inspecting and testing to assure that no asbestos hazard remained. You might want to ask for and read that report.

About the substance falling from your ceiling, if you think it's asbestos-containing material you certainly shouldn't be running a fan, and it would make sense to have it tested for asbestos content.

The % of asbestos number you cite leaves me confused. If you mean that the general dust from the environment is down to that minimal level, it sounds almost below the limits of detection. But I don't know what test you are describing, nor where nor how it was performed -those questions are key in understanding what the test results mean.

Your concern should be answered more specifically by a hygienist or similar professional who has specific expertise in asbestos and indoor air quality and who knows the building and its history.

We would much appreciate hearing any comments, critique, suggestions, or further questions from you or other readers. We are dedicated to making our information as accurate, complete, useful, and unbiased as possible: we very much welcome critique, questions, or content suggestions for our web articles. Working together and exchanging information makes us better informed than any individual can be working alone.

Reader follow-up:

Well this is my first year at this school, and was told that 2 years ago there was asbestos in the library and the music room and they did have it cleaned up professionally, but they didn't do it to the kitchen.

now this stuff that looks like your picture above with the gold and silver flakes in is is all over my kitchen and my boss told me it wasn't harmful cause they had it tested and it was at .0004%, but my concern is that if they had to clean it out of the other 2 rooms that it should be also done to my kitchen and i have 2 other ladies that work with me and we are all really concerned and are wondering what it is or whom it is that we can contact because everyone is telling us its ok and i don't think it is ok.

my boss is having someone come out there to caulk the ceiling again, and that is it...more or less just sweeping this under the rug. ..i have some of this stuff that fell from the ceiling in a plastic folder. it was hanging on the wall and caught it, but my concern is that i didn't know it was in there at the time i pulled a few papers out of it.

that is how it was brought to my attention of what it was. i am seriously concerned and would just like to know whom it is i need to contact outside the school, since no one in the school seems to really care about it or us.

Question: Zonolite Rolled Glass Fiber Home Insulation

i got zonolite rolled glass fiber home insulation is it safe ? - Concerned

Reply:

Concerned: I don't recognize the product you name - can you send me a photo of the material and of any labels or markings on packaging? Then I can research and comment further. Use the CONTACT US link at page top or bottom to send photos if you can.

Certainly "fiberglass" is not an asbestos material. In our opinion, fiberglass insulation is safe if it has been properly installed and has not been damaged. Severely damaged fiberglass insulation, such as a product that has been walked-upon numerous times, or that has been macerated during demolition, may produce high levels of glass fiber dust, including small particles that may are a respiratory irritant and may be more harmful.

Should I have my Attic Insulation Tested?

I found plastic bags in my attic space that say "Full Fill" Insulation 100% abestos free from Koos Inc. Kenosha, WI. Should I have the insulation tested? - Colleen 3/4/12

Reply: U.S. EPA Koos WI Site Visit Report on Vermiculite & Asbestos Exposure

Colleen, some mesothelioma and asbestosis websites, usually ones seeking to provide legal services, report that workers at Koos corporation in Wisconsin were exposed to dangerous levels of asbestos. The U.S. EPA visited the Koos site in Kenosha, WI on 9 March 2000. Here are two reports from the U.S. Government Accounting Office.

Unknown facility:

An EPA database compiled from W.R. Grace shipping invoices did not contain any records indicating Libby ore was shipped to this site. Because this site was associated with the Koos Inc. site in Kenosha, Wisconsin, EPA visited this site. (The Kenosha site is listed separately in this database) At the time of EPA's visit, IMC Salt, Inc. operated at this site.

The company warehoused and distributed packaged salt. According to company officials, IMC started operations at the site in 1995. Company officials were not aware of vermiculite ore being handled at this facility. EPA did not find any records indicating that Koos had operated at this site before 1995. On the basis of this information, EPA determined no further action was needed.[19]

Former Koos Inc. exfoliation facility, asbestos, & vermiculite

According to an EPA database compiled from W.R. Grace shipping invoices, 1,995 tons of vermiculite ore from the Libby mine were shipped to this site between April 1969 and March 1982.
In addition, reports published by the U.S. Geological Survey in 1975, 1980, 1985, and 1990 indicated that this facility had been a vermiculite exfoliation plant.

The site was about 10 acres and was bounded to the north by a street, to the east by railroad tracks, and to the west and south by businesses and residences. At the time of EPA's site visit, IMC Salt, Inc. was operating at the site. The site consisted of an office building, a warehouse and production area, a bulk storage building, and a maintenance shop.

According to IMC officials, IMC Vigaro purchased Koos, Inc. in 1995 and all exfoliation equipment was sold at that time. In 1998, IMC Salt, Inc. began salt packaging and warehousing operations at the site. From 1960 until 1995, Koos had exfoliated vermiculite at the facility and sold vermiculite wholesale. Exfoliated vermiculite was sold for use in fertilizer and in fire proof doors. Some of the exfoliated vermiculite waste had been placed in a local landfill.

An IMC official said Koos purchased vermiculite ore from American Vermiculite (a South African mine) and from W.R. Grace, but, to their knowledge, none of the ore came from the Libby mine. The ore was shipped to the facility by truck and rail and the exfoliation process was performed indoors. EPA did not see any evidence of vermiculite on the site.

On April 3, 2001, EPA collected five soil samples at the site and analyzed them using polarized light microscopy (PLM). None of the samples contained detectable levels of asbestos. On the basis of this information, EPA decided no further action was needed.[20]

Therefore, while the "safe answer" is to spend your money testing your insulation, and given only the information in your brief question, we caution that as we report in detail in the article above, even if your insulation is a vermiculite product (you did not say that it was), a bulk test can give a false negative result. Therefore the EPA and other experts advise that consumers assume that their vermiculite contains asbestos and follow EPA's advice to leave the material alone, undisturbed.

Question: What are the chances that vermiculite in our home came from the Libby Mine?

I have a house in Massachusetts that was constructed circa 1770. Local lore has it that there was an attic fire circa 1890. The wood work and plaster indicate that the attic was "finished" circa 1900. Some floor boards are missing, the floorboards are 1" hard pine, T&G. They also indicate late 19th, early 20th century. The floorboards were removed in the 1950's for electrical wiring (I am certain vermiculite was not added at that time). I can see about 1 1/2 inches of vermiculite between the joists.

I have spoken with a local resident who grew up in the house in the 1940's, when it did not have electricity. He tells me that heat was by way of a hot air furnace in the cellar which released heat through a large grate in the first floor. This also indicates late 19th century. I would assume that was when any attic insulation was added.

So,my question is. given the era what is the likelihood that the vermiculite came from the Libby mine which contained the asbestos? - Ralph Donaldson 5/5/12

Reply:

Ralph,

Considering the very wide-spread use of Zonolite as a retrofit building insulation product, it is certainly possible that it was used in your home.

Zonolite, which was found to contain tremolite asbestos, was produced in very large quantities, reaching 150,000 tons per year by 1950, and the plant continued to operate until 1990. There are other vermiculite mines that do not contain asbestos in their product and that continue to operate today.

It would be a mistake to presume that the Libby Montana Zonolite vermiculite mine source was the only source of asbestos containing products, including insulation, found in homes, as asbestos was used in a very wide range of building and in-home products and continues to appear in some products today.

And it might be an error to presume this is the most serious hazard in a home as well.

In our article above we report in detail on the occurrence of asbestos in Zonolite Attic Insulation (ZAI) produced by the Zonolite Company and by its successor owner- W.R. Grace Corporation between 1923 and 1990.

Watch out: It might be useful to have your vermiculite insulation tested. If the result shows Tremolite asbestos (vermiculite mined at Libby Montana had a 10% Tremolite asbestos content) that probably points to the Libby vermiculite mine. But the US EPA warns that bulk testing of vermiculite for asbestos content can sometimes lead to a false negative finding (failing to detect asbestos even though it is present). That's a reason that the US EPA warned that people should err on the side of caution, assuming that it is asbestos-contaminated.

We also are researching the question of whether or not one can report a contents profile that would let one assay a vermiculite sample and guess at its source - as can be done very accurately with roofing slates. We will add that information here.

Question: Insulation in a 1969 house looks like white and gray furry stuff - is this vermiculite or asbestos?

I am buying a house that was build in 1969. I have not tested the insulation yet (I will). However, it doesn't looks like any of the above pictures. It looks like white and gray and furry. Are there still chance for the insulation to contain vermiculite or asbestos? - Will 7/12/2012

Reply:

Will,

For help in identifying the type of insulation in your home, see our INSULATION IDENTIFICATION GUIDE . From your description you may be looking at Mineral Wool - Rock Wool Insulation.

Question: was asbestos-contaminated vermiculite imported into the U.K.?

Are you aware if any of this contaminated vermiculite was imported to the UK? Thank you. - Laurence 9/15/2012

Reply:

Sorry Laurence, no I don't know.

Typically, because of price competition and the importance of shipping costs, insulation products are produced and shipped from locations a bit closer to their point of use.

Question: where can I have a sample of vermiculite insulation to have it tested?

I recently purchased a house from HUD. I had my home inspected and found out there is exposed vermiculite in the basement that has fallen to the floor and is now been tracked around. Where can I take a sample of this insulation to have it tested ? - Tim 9/16/2012

Reply: Where to Find a Certified or Accredited Asbestos Testing Laboratory

Tim, you can use any test laboratory certified for asbestos testing. Both the US EPA and many U.S. states or Canadian provinces maintain lists of currently-approved asbestos testing labs.

Most state and provincial governments regulate and certify asbestos testing laboratories, and we recommend that where there are health, legal, or cost concerns, you should only use a certified and competent asbestos testing laboratory to examine material samples for asbestos content.

We give a list of several ways to find a certified asbestos test lab at ASBESTOS TEST LABS.

Question: worried sick after our home inspector tested our "vermiculite insulation" for asbestos - lab said it was cellulose

cellulose building insulationI recently bought a 1940s house which upon inspection was suspected to have vermiculita in a small area of the attic. The home inspector got it tested and it came back composed of cellulose and non fibrous materials, no asbestos. fast forward a few months we are now having our batting insulation replaced and the guys doing the work tell us its vermiculite.

What do we go by? we also had our contractor tell us that its not vermiculite...im worried sick that now that the batting insulation is being removed, asbestos fibers might flying all over our house! - Worried sick., 10/5/2012

Reply: cellulose is not vermiculite and is not asbestos; but one insulation sample may not represent all building insulation in the structure

Worried:

You might be best off trying to not be worried sick, as that itself may be an immediate health hazard and also invites opportunists who may price-gouge you when they see that you're terrified. Scared means costly.

Provided your home inspector used a qualified forensic or asbestos test lab (see Where to Find a Certified or Accredited Asbestos Testing Laboratory), I'd trust their lab result for the insulation sample that was actually tested.

I am a little surprised that your home inspector could not himself tell the very obvious difference between cellulose building insulation and vermiculite insulation. They are not at all visually similar.

Why did he test cellulose (Cellulose loose fill insulation - basically paper) for asbestos? Did he charge you a profit beyond the actual lab fee for that test?

I am not surprised that workers may have found vermiculite insulation in a 1940's house; Vermiculite was widely used as a pour-in insulation retrofit and often a 1940's home was originally built with little or no insulation to start with. In the 1970's many of us (including myself) added various insulation products, including vermiculite, in those homes.

By taking a look at the photographs in this article, even a child should be able to see the difference between vermiculite and other building insulation products. Our photo above shows a typical blown-in cellulose insulation installation. If indeed your workers are correct and vermiculite is in place, you should

Question: did Vermiculite Insulation sold in the U.K. (Ireland in this case) contain asbestos?

I hope you can help me with a query I have. [Paraphrasing at reader request]: there was a vermiculite spill in my home in Ireland. How do I make sure that the home has not been contaminated with asbestos?

Reply: Dust sampling theory: usefulness & definitions of "old dust" and "recent dust" in buildings & where these are found

In an effort to be more clear about dust sampling theory I have expanded the descriptions of old dust, recent dust, where such samples are usually found, and why one would collect them for analysis - that discussion is now found at

DUST SAMPLE TYPES

In short, if you were worried that an original vermiculite spill had not been adequately cleaned, *or* if you wanted to know if the original vermiculite spill included asbestos, you might want to collect both a recent-dust sample and an old dust sample for comparison.

If, however, the cleanup was professionally conducted and post-cleanup testing was already performed properly, and if those steps indicated no problem remaining, in my *opinion* further testing would not be justified unless a new reason for further investigation is apparent. (Examples of such reasons are

at MOLD / ENVIRONMENTAL EXPERT, HIRE ? 

and also at MOLD TEST REASONS.

Reader follow-up:

The vermiculite spill was not professionally cleaned, and was swept and vacuumed with a standard household vacuum cleaner by the plumber before I ever knew what vermiculite was

Reply:

Thanks for the follow-up; Ordinary vacuuming actually increases the level of fine particulates; HEPA vacuuming would have been in order if we thought that asbestos was present, along with damp wiping of horizontal surfaces.

Most likely, from your case history, you're ok. If you want to get a settled-dust sample analyzed just send it to a certified asbestos testing laboratory and allow them to choose their method of analysis; typically the lab uses polarized light microscopy following the Walter McCrone procedure.

Some asbestos test labs may also make use of other methods such as SEM; any certified lab will use appropriate asbestos identification procedures - as an amateur I would not second guess the lab ty telling them what to do, just make sure the sample is collected and question posed following their requrested procedure.


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