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

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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.

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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 (Spitze 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 physist described vermiculite (Hermann 1828) and Ten years after Webb, Bunsen, a German physist, 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 Zononlite 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 Eary 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


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

Noborio (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.

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