Vermiculite
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Vermiculite is a
hydrous In chemistry, a hydrate is a substance that contains water or its constituent elements. The chemical state of the water varies widely between different classes of hydrates, some of which were so labeled before their chemical structure was underst ...
phyllosilicate Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. In mineralogy, silica (silicon dioxide, ) is usually consid ...
mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. ( ...
which undergoes significant expansion when heated. Exfoliation occurs when the mineral is heated sufficiently, and commercial furnaces can routinely produce this effect. Vermiculite forms by the
weathering Weathering is the deterioration of rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs ''in situ'' (on site, with little or no movement), ...
or
hydrothermal alteration Metasomatism (from the Greek μετά ''metá'' "change" and σῶμα ''sôma'' "body") is the chemical alteration of a rock by hydrothermal and other fluids. It is the replacement of one rock by another of different mineralogical and chemical co ...
of
biotite Biotite is a common group of phyllosilicate minerals within the mica group, with the approximate chemical formula . It is primarily a solid-solution series between the iron-endmember annite, and the magnesium-endmember phlogopite; more alumino ...
or
phlogopite Phlogopite is a yellow, greenish, or reddish-brown member of the mica family of phyllosilicates. It is also known as magnesium mica. Phlogopite is the magnesium endmember of the biotite solid solution series, with the chemical formula KMg3AlSi3O ...
. http://www.mindat.org/min-4170.html Mindat.org Large commercial vermiculite mines currently exist in the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
,
Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...
,
South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...
,
China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
, and
Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
.


Occurrence

Vermiculite was first described in 1824 for an occurrence in
Millbury, Massachusetts Millbury, officially the Town of Millbury, is a town in Worcester County, Massachusetts. Located within Blackstone Valley, the population in Millbury was 13,831 at the 2020 United States Census. History Millbury was first settled by Europea ...
. Its name is from
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
, "to breed worms", for the manner in which it exfoliates when heated. It typically occurs as an alteration product at the contact between felsic and
mafic A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include ...
or
ultramafic Ultramafic rocks (also referred to as ultrabasic rocks, although the terms are not wholly equivalent) are igneous and meta-igneous rocks with a very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium, and are composed ...
rocks such as
pyroxenite Pyroxenite is an ultramafic igneous rock consisting essentially of minerals of the pyroxene group, such as augite, diopside, hypersthene, bronzite or enstatite. Pyroxenites are classified into clinopyroxenites, orthopyroxenites, and the we ...
s and
dunite Dunite (), also known as olivinite (not to be confused with the mineral olivenite), is an intrusive igneous rock of ultramafic composition and with phaneritic (coarse-grained) texture. The mineral assemblage is greater than 90% olivine, with ...
s. It also occurs in
carbonatite Carbonatite () is a type of intrusive or extrusive igneous rock defined by mineralogic composition consisting of greater than 50% carbonate minerals. Carbonatites may be confused with marble and may require geochemical verification. Carbonati ...
s and
metamorphosed Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causi ...
magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...
-rich
limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...
. Associated mineral phases include:
corundum Corundum is a crystalline form of aluminium oxide () typically containing traces of iron, titanium, vanadium and chromium. It is a rock-forming mineral. It is a naturally transparent material, but can have different colors depending on the pres ...
,
apatite Apatite is a group of phosphate minerals, usually hydroxyapatite, fluorapatite and chlorapatite, with high concentrations of OH−, F− and Cl− ions, respectively, in the crystal. The formula of the admixture of the three most common e ...
, serpentine, and
talc Talc, or talcum, is a Clay minerals, clay mineral, composed of hydrated magnesium silicate with the chemical formula Mg3Si4O10(OH)2. Talc in powdered form, often combined with corn starch, is used as baby powder. This mineral is used as a thi ...
. It occurs interlayered with chlorite, biotite and phlogopite.http://rruff.geo.arizona.edu/doclib/hom/vermiculite.pdf Handbook of Mineralogy


Structure

Vermiculite is a 2:1
clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay par ...
, meaning it has two
tetrahedral In geometry, a tetrahedron (plural: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertex corners. The tetrahedron is the simplest of all the ...
sheets for every one
octahedral In geometry, an octahedron (plural: octahedra, octahedrons) is a polyhedron with eight faces. The term is most commonly used to refer to the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet a ...
sheet. It is a limited-expansion clay with a medium
shrink–swell capacity The shrink–swell capacity of soils refers to the extent certain clay minerals will expand when wet and retract when dry. Soil with a high shrink–swell capacity is problematic and is known as shrink–swell soil, or expansive soil. The amount o ...
. Vermiculite has a high
cation-exchange capacity Cation-exchange capacity (CEC) is a measure of how many cations can be retained on soil particle surfaces. Negative charges on the surfaces of soil particles bind positively-charged atoms or molecules (cations), but allow these to exchange with ot ...
(CEC) at 100–150
meq An equivalent (symbol: officially equiv; unofficially but often Eq) is the amount of a substance that reacts with (or is ''equivalent'' to) an arbitrary amount (typically one mole) of another substance in a given chemical reaction. It is an arc ...
/100 g. Vermiculite clays are weathered
mica Micas ( ) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into extremely thin elastic plates. This characteristic is described as perfect basal cleavage. Mica is ...
s in which the
potassium Potassium is the chemical element with the symbol K (from Neo-Latin ''kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmosphe ...
ions between the molecular sheets are replaced by magnesium and
iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...
ions.


Commercial uses


Molded shapes

This process involves mixing exfoliated vermiculite with inorganic bonding agents such as sodium silicate, cement (specific quantities), and other compounds, such as those containing potassium, to produce an 'earth damp' mixture. This material is then hydraulically pressed into shape in a mold and then heat cured at temperatures up to 180 °C for up to 24 hours, depending upon the thickness of the moulded part. Such parts can withstand service temperatures of up to 1150 °C and are often used in the aluminium smelting industry as back-up insulation behind the carbon cathode in the pot cells which contain the molten mixture of cryolite and alumina. The moulded shapes and boards are used in: * Open fireplaces * High-temperature or
refractory In materials science, a refractory material or refractory is a material that is resistant to decomposition by heat, pressure, or chemical attack, and retains strength and form at high temperatures. Refractories are polycrystalline, polyphase, ...
insulation * Acoustic panels *
Fireproofing Fireproofing is rendering something (structures, materials, etc.) resistant to fire, or incombustible; or material for use in making anything fire-proof. It is a passive fire protection measure. "Fireproof" or "fireproofing" can be used as a n ...
of structural
steel Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant ty ...
and
pipes Pipe(s), PIPE(S) or piping may refer to: Objects * Pipe (fluid conveyance), a hollow cylinder following certain dimension rules ** Piping, the use of pipes in industry * Smoking pipe ** Tobacco pipe * Half-pipe and quarter pipe, semi-circula ...


Calcium silicate boards

Exfoliated vermiculite is added to a
calcium silicate Calcium silicate is the chemical compound Ca2SiO4, also known as calcium orthosilicate and is sometimes formulated as 2CaO·SiO2. It is also referred to by the shortened trade name Cal-Sil or Calsil. It occurs naturally as the mineral larnite. ...
slurry. This is then dewatered by pressing or by using one of the Fourdriner/Magnani/Hatschek processes to form a flat board which is then heat cured under pressure (typically 10–15 bar) for periods of up to 24 hours.


Brake linings

Finer grades of exfoliated vermiculite are being used in
brake lining Brake linings are the consumable surfaces in brake systems, such as drum brakes and disc brakes used in transport vehicles. History Brake linings were invented by Bertha Benz (the wife of Karl Benz, who invented the first patented automobile) du ...
s primarily for the automotive market. The properties of vermiculite that make it an appropriate choice for use in brake linings include its thermal resistance, ease of addition to other raw materials to achieve a homogeneous mix, and its shape and surface characteristics.


Roof and floor screeds and insulating concretes

Exfoliated vermiculite (typically the finer grades) can be added at site to
Portland cement Portland cement is the most common type of cement in general use around the world as a basic ingredient of concrete, mortar, stucco, and non-specialty grout. It was developed from other types of hydraulic lime in England in the early 19th c ...
and other aggregates,
rheological Rheology (; ) is the study of the flow of matter, primarily in a fluid (liquid or gas) state, but also as "soft solids" or solids under conditions in which they respond with plastic flow rather than deforming elastically in response to an appli ...
aids, and water to produce roof and floor concrete
screed Screed has three meanings in building construction: # A flat board (screed board, floating screed) or a purpose-made aluminium tool used to smooth and to "true" materials like concrete, stucco and plaster after they have been placed on a surface ...
s which are lightweight and insulating. In many cases, vermiculite-based roof screeds are used in conjunction with other insulation materials, such as
polystyrene Polystyrene (PS) is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin per unit weight. It is a ...
board, to form a total roofing system. A
bituminous Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term a ...
binder can also be used with exfoliated vermiculite to produce a dry, lightweight roof screed which has the advantages of low thermal conductivity, low moisture content, and ease of placement (by pouring from the bag and then tamping).


Soilless growing medium

Exfoliated vermiculite is combined with other materials such as
peat Peat (), also known as turf (), is an accumulation of partially decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, moors, or muskegs. The peatland ecosystem covers and is the most efficien ...
or composted pine bark to produce soilless growing medium for the professional horticulturalist and for the home gardener. These mixes promote faster root growth and give quick anchorage to young roots. The mixture helps retain air, plant food, and moisture, releasing them as the plant requires them. These mixes were pioneered by Boodley and Sheldrake. Exfoliated vermiculite is also used as a growing medium for hydroponics.


Seed germination

Vermiculite, alone or mixed with soil or peat, is used to germinate seeds; very little watering is required. When vermiculite is used alone,
seedling A seedling is a young sporophyte developing out of a plant embryo from a seed. Seedling development starts with germination of the seed. A typical young seedling consists of three main parts: the radicle (embryonic root), the hypocotyl (embry ...
s should be fed with a weak fertilizer solution when the first true leaves appear, e.g. with one teaspoon of 5-10-5
soluble In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solubil ...
fertilizer A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from ...
per gallon of water, gradually increased to one tablespoon (1:256 ratio) when transplanting.


Root crop storage

Pour vermiculite around bulbs placed in container. If clumps are dug, allow to dry for a few hours in the sun and then place in cartons or bushel baskets and cover with vermiculite. The absorptive power of vermiculite acts as a regulator that prevents
mildew Mildew is a form of fungus. It is distinguished from its closely related counterpart, mould, largely by its colour: moulds appear in shades of black, blue, red, and green, whereas mildew is white. It appears as a thin, superficial growth consi ...
and moisture fluctuation during the storage period. It will not absorb moisture from the inside of stored tubers, but it does take up free water from the outside, preventing storage rot.


Soil conditioner

Where the native soil is heavy or sticky, gentle mixing of vermiculite as a soil conditioner —up to one-half the volume of the soil—is recommended. This creates air channels and allows the soil mix to breathe. Mixing vermiculite in flower and vegetable gardens or in
potted Potting may refer to: * Potting, in pottery, the making of pots, generally on the potter's wheel * Potting (electronics), the encapsulation of electronic components * In farming and gardening, potting is planting a plant in a pot, such as a flowe ...
plants will provide the necessary air to maintain vigorous plant growth. Where soils are sandy, mixing of vermiculite into the soil will allow the soil to hold the water and air needed for growth.


As loose-fill insulation

Exfoliated vermiculite treated with a water repellent is used to fill the pores and cavities of masonry construction and hollow blockwork to enhance fire ratings (e.g. Underwriters Laboratories Wall and Partition designs), thermal insulation, and acoustic performance. Expanded vermiculite has also been used as thermal insulation in the attics and walls of houses and in water heaters, fire safes, stoves, furnaces, and refrigerators.


Refractory/Insulation gunning and castable mixes

Exfoliated vermiculite can be combined with high alumina (also known as calcium aluminate) cements and other aggregates such as expanded
shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especial ...
,
clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay par ...
, and
slate Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism. It is the finest grained foliated metamorphic rock. ...
or sodium silicate to produce refractory/insulation concretes and mortars. In the early days of their use, these products were batched at or very close to the place of installation. This continues to be the case in some limited circumstances; however, more and more use is being made of pre-batched, proprietary mixes. Mixes containing vermiculite are used in areas where strength and corrosion/abrasion resistance are of secondary importance, the most important factor being the insulation performance of the in-place refractory lining. These mixes are used in industries including iron/steel, cement, and hydrocarbon processing.


Fireprotection

As an additive to fireproof
wallboard Drywall (also called plasterboard, dry lining, wallboard, sheet rock, gypsum board, buster board, custard board, and gypsum panel) is a panel made of calcium sulfate dihydrate (gypsum), with or without additives, typically extruded between thick ...
.


High temperature coating

Vermiculite dispersions are typically either chemically or physically very finely delaminated vermiculite in a fluid medium. These dispersions can be used to make vermiculite 'paper' sheets by pouring them onto a piece of smooth, low surface-energy plastic, and allowing to dry. The resulting sheet can then be peeled off the plastic. Typical end-uses for vermiculite dispersions include inclusion in high temperature coatings or binders for construction materials, gaskets, specialty papers/textiles, oxidation-resistant coating on carbon based composites, and as barrier coatings for films.


Waste treatment

Waste treatment: the cation exchange capacity (up to 1,000 milliequivalents per kg) of vermiculite allows it to be used in fluid purification processes for waste water, chemical processing, and the pollution-control of air in mines and gases in industrial processes. In addition to its ion exchange properties, exfoliated vermiculite can retain liquids within the inter-laminar voids of the individual particles, as well as between the particles themselves.


Others

* As a packing material, valued for its high absorbency. * As a substrate for various animals and/or a medium for incubation of eggs. * As a lightweight aggregate for
plaster Plaster is a building material used for the protective or decorative coating of walls and ceilings and for Molding (decorative), moulding and casting decorative elements. In English, "plaster" usually means a material used for the interiors of ...
, proprietary
concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wi ...
compounds,
firestop A firestop or fire-stopping is a form of passive fire protection that is used to seal around openings and between joints in a fire-resistance-rated wall or floor assembly. Firestops are designed to maintain the fire-resistance rating of a wall ...
mortar, and cementitious spray fireproofing: Exfoliated vermiculite is used in both hand and spray-applied general building plasters to improve coverage, ease of handling, adhesion to a wide variety of substrates, fire resistance, and resistance to chipping/cracking/shrinkage. * As a component of the interior fill for
firestop pillow Firestop pillows are passive fire protection items used for firestopping holes to achieve fireproofing. The various kinds of firestop pillows are intended to slow the spread of fire. They are often used to meet fire-resistance ratings in condu ...
s, along with
graphite Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on large ...
. * As a carrier for dry handling and slow release of agricultural chemicals. * As a ''hot topping'': both exfoliated and crude vermiculite have been used for ''hot topping'' in the steel industry. When poured onto molten metal, crude vermiculite exfoliates immediately and forms an insulating layer, allowing the material to be transported to the next production process without losing too much heat. * Used to permit slow cooling of hot pieces in
glassblowing Glassblowing is a glassforming technique that involves inflating molten glass into a bubble (or parison) with the aid of a Blowpipe (tool), blowpipe (or blow tube). A person who blows glass is called a ''glassblower'', ''glassmith'', or ''gaffer'' ...
,
lampwork Lampworking is a type of glasswork in which a torch or lamp is used to melt the glass. Once in a molten state, the glass is formed by blowing and shaping with tools and hand movements. It is also known as flameworking or torchworking, as the moder ...
, steelwork, and
glass beadmaking Glass bead making has long traditions, with the oldest known beads dating over 3,000 years. Glass beads have been dated back to at least Roman times. Perhaps the earliest glass-like beads were Egyptian faience beads, a form of clay bead with a ...
. * Used in in-ground swimming pools to provide a smooth pool base: Finer grades of exfoliated vermiculite plus Portland cement may be combined either on-site or in a factory premix to provide a base for swimming pool vinyl liners. These mixes are pumped into place using a rotor stator pump, or hand poured. * Used in commercial
hand warmer Hand warmers are small (mostly disposable) packets which are held in the hand and produce heat on demand to warm cold hands. They are commonly used in outdoor activities. Other types of warmers are available to provide soothing heat for muscular ...
s. * Used in
AGA cooker The AGA cooker oven is a Swedish oven and cooker. Invented and initially produced in Sweden, since 1957 all production has been located in the UK. History Originally developed to burn coal or anthracite, the Aga cooker was invented in 1922 by ...
s as insulation. * Used in explosives storage as a blast mitigant. * Used to absorb hazardous liquids for solid disposal. * Used in gas fireplaces to simulate embers. * Used as part of a substrate for cultivation of
fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...
.


Commercial manufacture of exfoliated vermiculite

In 2014, South Africa, Brazil, the US, and China were the top producers of mined, concentrated and unexfoliated vermiculite, with about 90% world share. South Africa's production is decreasing, while Brazil's is significantly increasing. While some end processors and exfoliators of vermiculite specialize, with proprietary products sold in a wide variety of industries, some have more varied end products, with less stringent technical requirements. Some vermiculite exfoliators blend with lower-cost
perlite Perlite is an amorphous volcanic glass that has a relatively high water content, typically formed by the hydration of obsidian. It occurs naturally and has the unusual property of greatly expanding when heated sufficiently. It is an industrial m ...
also. Vermiculite exfoliators have an international trade association called ''The Vermiculite Association'' to represent the industry's interests and to exchange information.


Fireproofing

Today spray-applied
fireproofing Fireproofing is rendering something (structures, materials, etc.) resistant to fire, or incombustible; or material for use in making anything fire-proof. It is a passive fire protection measure. "Fireproof" or "fireproofing" can be used as a n ...
materials use vermiculite, other industrial minerals, and expanded polystyrene, depending upon the exact commercial product. The ingredients for these products all have to meet stringent regulatory requirements, particularly in the US and Europe. In the past, vermiculite from the W. R. Grace mines in Libby, Montana, has been associated with
asbestos Asbestos () is a naturally occurring fibrous silicate mineral. There are six types, all of which are composed of long and thin fibrous crystals, each fibre being composed of many microscopic "fibrils" that can be released into the atmosphere b ...
. Therefore, old spray-applied fireproofing, pre-1991, may contain small quantities of asbestos. In August 2014, the NYSDoH qualified two, more exact, test methods, better designed to identify materials with this potential problem, and assist in safely dealing with any issues associated with its removal. Modern spray applied fireproofing today is made with various light weight aggregates that does not contain asbestos and is carefully monitored at all stages of mining and production to ensure this is the case.


Asbestos contamination

Although not all vermiculite contains
asbestos Asbestos () is a naturally occurring fibrous silicate mineral. There are six types, all of which are composed of long and thin fibrous crystals, each fibre being composed of many microscopic "fibrils" that can be released into the atmosphere b ...
, 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
tremolite Tremolite is a member of the amphibole group of silicate minerals with composition: Ca2(Mg5.0-4.5Fe2+0.0-0.5)Si8O22(OH)2. Tremolite forms by metamorphism of sediments rich in dolomite and quartz. Tremolite forms a series with actinolite and fe ...
asbestos as well as winchite and richterite (both fibrous
amphibole Amphibole () is a group of inosilicate minerals, forming prism or needlelike crystals, composed of double chain tetrahedra, linked at the vertices and generally containing ions of iron and/or magnesium in their structures. Its IMA symbol is A ...
s)—in fact, it was formed underground through essentially the same geologic processes as the contaminants. Pure vermiculite does not contain asbestos and is non-toxic. Impure vermiculite may contain, apart from asbestos, also minor
diopside Diopside is a monoclinic pyroxene mineral with composition . It forms complete solid solution series with hedenbergite () and augite, and partial solid solutions with orthopyroxene and pigeonite. It forms variably colored, but typically dull ...
or remnants of the precursor minerals
biotite Biotite is a common group of phyllosilicate minerals within the mica group, with the approximate chemical formula . It is primarily a solid-solution series between the iron-endmember annite, and the magnesium-endmember phlogopite; more alumino ...
or
phlogopite Phlogopite is a yellow, greenish, or reddish-brown member of the mica family of phyllosilicates. It is also known as magnesium mica. Phlogopite is the magnesium endmember of the biotite solid solution series, with the chemical formula KMg3AlSi3O ...
.


Controversy over health risks

The largest and oldest vermiculite mine in the United States was started in the 1920s, at Libby, Montana, and the vermiculite was sold under the commercial name Zonolite. The Zonolite brand and the mine were acquired by the
W. R. Grace and Company W. R. Grace and Co. is an American chemical business based in Columbia, Maryland. It produces specialty chemicals and specialty materials in two divisions: Grace Catalysts Technologies, which makes catalysts and related products and technologies ...
in 1963. Mining operations at 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. 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. An article published in ''
The Salt Lake Tribune ''The Salt Lake Tribune'' is a newspaper published in the city of Salt Lake City, Utah. The ''Tribune'' is owned by The Salt Lake Tribune, Inc., a non-profit corporation. The newspaper's motto is "Utah's Independent Voice Since 1871." History ...
'' on December 3, 2006, reported that vermiculite and Zonolite 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 and others regarding the health risks associated with vermiculite and that several sites in the Salt Lake Valley had been remediated by the
EPA The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it be ...
when they were shown to be contaminated with asbestos. W. R. Grace and Company has vigorously denied these charges. The vermiculite deposit at the mine in Libby, Montana, was (and is) heavily contaminated with asbestos. Numerous people were knowingly 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 and Company in 1963. Yet, knowing the human health risks, the mining company still continued to operate there until 1990. Consequently, many of the former miners and residents of Libby have been affected and continue to suffer health problems. Over 400 people in the town have 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 Tremolite is a member of the amphibole group of silicate minerals with composition: Ca2(Mg5.0-4.5Fe2+0.0-0.5)Si8O22(OH)2. Tremolite forms by metamorphism of sediments rich in dolomite and quartz. Tremolite forms a series with actinolite and fe ...
(known to be a very hazardous 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. After a 1999 ''
Seattle Post-Intelligencer The ''Seattle Post-Intelligencer'' (popularly known as the ''Seattle P-I'', the ''Post-Intelligencer'', or simply the ''P-I'') is an online newspaper and former print newspaper based in Seattle, Washington, United States. The newspaper was foun ...
'' story claimed that asbestos-related disease was common in the town, the
EPA The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it be ...
, 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. The EPA has spent $120 million in
Superfund Superfund is a United States federal environmental remediation program established by the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA). The program is administered by the United States Environmental Pro ...
money on cleanup. In October 2006, W. R. Grace and Company tried to appeal the fines ($54.5 million) levied on them from the EPA, but the Supreme Court rejected the appeal. The
United States government The federal government of the United States (U.S. federal government or U.S. government) is the national government of the United States, a federal republic located primarily in North America, composed of 50 states, a city within a fede ...
pursued criminal charges against several former executives and managers of the mine for allegedly disregarding and covering up health risks to employees. They were also accused of wire fraud, and of obstructing the government's cleanup efforts. As of the indictment date, about 1,200 residents of the Libby area had been identified as suffering from some kind of asbestos-related abnormality. The case ended in acquittals on May 8, 2009. On June 17, 2009, the EPA issued a public health emergency in and near Libby, thereby allowing federal agencies to provide funding for health care, and for removal of contaminated insulation from affected homes.Dean, Cornelia
U.S. Cites Emergency in Asbestos-Poisoned Town
''
The New York Times ''The New York Times'' (''the Times'', ''NYT'', or the Gray Lady) is a daily newspaper based in New York City with a worldwide readership reported in 2020 to comprise a declining 840,000 paid print subscribers, and a growing 6 million paid ...
'', June 18, 2009.


See also

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References


External links


The Vermiculite Association

US Geological Survey Vermiculite Section

United States Environmental Protection Agency

Petition for writ of certiorari to U.S. Supreme Court (April 27, 2006)
{{Authority control Aluminium minerals Asbestos Industrial minerals Iron(II,III) minerals Magnesium minerals Mica group Monoclinic minerals Minerals in space group 12 Passive fire protection Soil improvers