No fee unless we recover compensation for your family Text size 833-4-ASBESTOS (833-427-2378) Free Case Review

Amosite: Brown Asbestos and the US Navy

Reviewed by Justinian C. Lane, Attorney Last reviewed June 2026

Amosite, also called brown asbestos, is one of the six minerals regulated as asbestos under US law. It's an iron-rich amphibole fiber that came from a single region in South Africa, the only place on Earth it was ever mined commercially. Amosite was used overwhelmingly for one thing: high-temperature insulation, especially the pipe and boiler insulation on US Navy ships and in power plants, refineries, and chemical plants. Like every form of asbestos, it causes mesothelioma (a cancer of the lining of the lungs or abdomen), lung cancer, and asbestosis (permanent scarring of the lungs).1 The people most heavily exposed were insulators, shipyard workers, and Navy veterans, and it's still in older ships, buildings, and industrial facilities today.

If you worked as an insulator, in a shipyard, or aboard Navy ships, or in a power plant, refinery, or chemical plant, and you've been diagnosed with an asbestos disease, call 833-4-ASBESTOS to find out whether you have a claim.

6:17
Watch Amosite Asbestos Came From South Africa (6:17)

You don't need the product names or old records. No fee unless we recover compensation for your family.

Call 833-4-ASBESTOS Request a review

The Paterson plant and what the company knew

When Japan attacked Pearl Harbor in December 1941, the US fleet had to be rebuilt at a speed no one had imagined, and every new warship needed thousands of feet of high-temperature pipe insulation. The only fiber that could do the job was amosite. The government had the Union Asbestos and Rubber Company, Unarco, open a plant in Paterson, New Jersey to weave amosite insulation for the fleet, and sent a young engineer named Robert Cryor to run it. Over the next four years, 933 men worked there. Most had no idea what the mineral would do to them.

The plant's own doctor did. He was a radiologist, hired to x-ray the workers when they started and every six months after. Within a year or two, what he saw on the films alarmed him: several men already had permanent lung scarring. He diagnosed asbestosis and told the attorney who had helped bring the plant to town to get the men out, because they were going to die horrible deaths.2

The attorney took the findings to Johns-Manville, the largest asbestos company in the world, to see how it handled the same problem. At a meeting around 1942 or 1943, Johns-Manville's general counsel, Vandiver Brown, confirmed that the company's own examinations had found the same disease in its own workers. A Johns-Manville plant study a decade earlier had already found asbestosis in roughly one of every three workers examined. Brown explained that it was company policy to do nothing and to say nothing, because warning workers would only lead them to stop working and file claims. Asked whether he really meant he would let the men work until they dropped dead, he answered, by the attorney's later sworn account, "Yes. We save a lot of money that way." The Unarco men were then taken to lunch in the company boardroom, where, in a time of wartime rationing, they were served lobster. The message was to stay quiet.2

Robert Cryor stayed quiet. He went on to a long career in the asbestos industry: president of the Asbestos Textile Institute in 1951–52, then founder in 1953 of the North American Asbestos Corporation. When he died in 1970, his obituary in the industry's trade journal called it the largest distributor of amosite and crocidolite in the Western Hemisphere, and a member of the Cape Asbestos group, the British company that mined amosite in South Africa. The men he managed in Paterson were not so fortunate, and decades later, science remembered them. A 1979 study followed 820 of the Paterson workers for 35 years. The findings were stark. Men who had worked at the plant for as little as one month died of lung cancer at nearly triple the expected rate. Of the men who worked two years or more, the researchers found the group "close to extinction" at 35 years: 85 percent were dead, against an expected 59 percent. Across the whole group, 186 men died of asbestos diseases where fewer than 58 such deaths would have been expected. None of them had ever been warned.3

This is the heart of amosite's story, and it isn't only history. The reason these companies are liable today is that they knew, in writing, what their product did, and chose to protect the supply chain instead of the workers.

For an overview of all six asbestos minerals and the diseases they cause, see our main asbestos minerals page.

What is amosite?

Amosite is the fibrous form of a mineral called grunerite. It belongs to the amphibole branch of the asbestos family, so its fibers are straight, stiff, and needle-like, the kind the lungs can't easily clear.4 It's rich in iron, roughly 40 percent iron by weight, which gives it a brown color (hence "brown asbestos") and makes it stand up to seawater and heat. Its fibers are also unusually long, among the longest of any asbestos, which is why it could be woven into insulation blankets and felt.

Amosite is unusual among the six in another way: it came from only one place. The name itself is a clue. "Amosite" comes from "Amosa," short for Asbestos Mines of South Africa. Every ounce of commercial amosite in the world was mined in the Transvaal region of South Africa. It was named in 1918 by the geologist Albert Hall, who correctly figured it was a form of the iron amphibole grunerite.5

The mineralogy in depth: chemistry, crystal structure, and how amosite compares to the other five asbestos minerals

Chemical composition

Amosite's chemical formula is (Fe,Mg)₇Si₈O₂₂(OH)₂, which makes it an iron magnesium silicate in the amphibole group.6 The "(Fe,Mg)" means iron and magnesium share the same slots in the crystal, with iron strongly dominant. That high iron content, around 40 percent by weight, does three things: it gives amosite its brown color, it makes the fiber resist seawater (which is why the Navy valued it), and it makes the fiber chemically reactive once it's in the body. Iron in lung tissue helps drive the production of unstable molecules that damage DNA, which is part of why iron-rich amphiboles like amosite are linked to high mesothelioma rates.

Amosite has the exact same formula as anthophyllite, just with iron dominant instead of magnesium. They're chemical mirror images: amosite is the iron-rich version, anthophyllite the magnesium-rich version. The underlying mineral, grunerite, was first described in 1847 and formally named in 1863 for the chemist Emmanuel-Louis Gruner.7,8

Crystal structure

Like all amphiboles, amosite is built from double chains of silicon and oxygen, held together by iron and magnesium. It crystallizes in the "monoclinic" form. This is worth getting right, because it's often stated incorrectly: amosite (grunerite) is monoclinic, while its magnesium-rich twin anthophyllite is orthorhombic. The two are essentially the same composition in two different crystal forms. Among the six regulated asbestos minerals, anthophyllite is the only orthorhombic one; the rest, amosite included, are monoclinic. The distinction doesn't change the hazard. Amosite's fibers are straight, rigid, and long, which is exactly the shape that lodges deep in the lungs and stays there.

How amosite compares to the other asbestos minerals

Mineral Chemical formula Main metals Crystal system Mineral group
Amosite (Fe,Mg)₇Si₈O₂₂(OH)₂ Iron, magnesium Monoclinic Amphibole
Anthophyllite (Mg,Fe)₇Si₈O₂₂(OH)₂ Magnesium, iron Orthorhombic Amphibole
Crocidolite Na₂Fe₃²⁺Fe₂³⁺Si₈O₂₂(OH)₂ Sodium, iron Monoclinic Amphibole
Tremolite Ca₂Mg₅Si₈O₂₂(OH)₂ Calcium, magnesium Monoclinic Amphibole
Actinolite Ca₂(Mg,Fe)₅Si₈O₂₂(OH)₂ Calcium, magnesium, iron Monoclinic Amphibole
Chrysotile Mg₃Si₂O₅(OH)₄ Magnesium Monoclinic Serpentine

The iron that made amosite valuable to industry is the same iron that makes it harmful in the body. It let insulation survive decades in hot, wet, salty conditions without breaking down, and it makes the fiber both long-lasting and chemically reactive once inhaled.

Physical properties

Property Value What it meant
Color Brown to grayish-brown The brown comes from iron; gives "brown asbestos" its name
Luster Vitreous to silky Fibrous masses have a silky sheen
Hardness About 5 to 6 (Mohs scale) Typical for the amphiboles
Specific gravity 3.4 to 3.5 Higher than chrysotile
Fiber length Unusually long Among the longest of any asbestos; could be woven
Heat resistance Stable to about 1,200°F Suited to high-temperature insulation
Seawater resistance Excellent Better than chrysotile, which made it the Navy's choice

Where amosite came from and what it was used for

All commercial amosite came from the Transvaal region of South Africa, mostly from the Penge mine, which by the late 1950s was the largest amosite producer in the world. Mining ran from about 1915 until the last amosite was mined in 1992.9 From there it was shipped to the United States and a handful of other countries.

A big reason amosite mattered in America was the US Navy. Between the World Wars, an arms-control treaty capped how much warships could weigh, so every pound saved on insulation freed up weight for armor, guns, or fuel. Amosite insulation weighed far less than the alternatives while handling the same heat, so the Navy specified it for shipboard use and kept specifying it for decades, through World War II and the Cold War. That single decision put amosite into hundreds of thousands of shipyard workers' and sailors' workplaces.10 Johns-Manville used about 23 percent of all the amosite consumed in the United States in its own plants, a 1988 company memo says, "primarily in insulation products, particularly in the lightweight insulations required by the Navy."

Because it held up to heat, moisture, and corrosive chemicals, amosite went into a focused set of products, almost all of them insulation:

  • 85 percent magnesia pipe and block insulation. The signature amosite product, used on steam pipes, boilers, and industrial equipment across power plants, factories, and ships.
  • Unibestos. A pipe insulation made of about 95 percent amosite, manufactured by Pittsburgh Corning and used heavily in refineries, chemical plants, and power plants because it resisted acid and wouldn't shrink or crumble.
  • Kaylo. A calcium-silicate pipe and block insulation made with amosite, sold by Owens-Illinois and later Owens-Corning, installed in refineries, power plants, shipyards, and industrial facilities for decades.
  • Marinite. A dense, fireproof structural board made by Johns-Manville, used for bulkheads and firewalls on ships and in buildings.
  • Spray-applied fireproofing. Sprayed onto structural steel in commercial buildings into the 1970s, which exposed the workers applying it and everyone who later renovated or demolished those buildings.
  • Asbestos-cement products, asphalt roofing felts, and acoustic materials. Smaller uses that still put amosite into buildings.

For more on the kinds of products that contained asbestos, see our guide to asbestos-containing products.

The full record: the South African mines, the corporate owners, mining conditions, and the government stockpile

The mineral content on this site draws on a systematic review of 88 consecutive USGS Minerals Yearbook chapters on asbestos, spanning 1932 through 2024, the complete run of the federal government's annual reporting on the asbestos industry. The record on amosite is unusually clean, because the supply chain was so concentrated: one mining region, a small number of importers, and a short list of product categories.11

The mines and their owners

The Transvaal amosite belt was worked from 1915 onward, with the Penge mine as the main operation. The mines passed through a chain of corporate owners that connects directly to the rest of the asbestos industry. The deposits were consolidated under the British company Cape Asbestos in 1925. Cape also mined blue asbestos in South Africa, which means knowledge of disease from one fiber sat with the same people running the other. Ownership later passed to other South African entities, and by 1981 a single group, Gencor, had bought up essentially every asbestos mine in the country. Amosite mining ended in 1992 when Japan, the last major buyer, stopped purchasing it, and South Africa later banned asbestos entirely.12

Mining conditions

The human cost began at the source. The early Transvaal mines were in remote terrain and operated under a system that kept workers outside the protections of mining law. Men dug fiber by hand, women separated it from the rock, and children sorted and packed it. Entire families, including small children, breathed heavy concentrations of amosite dust. A 1949 government inspection of the Penge mine described children inside shipping bags trampling down loose amosite as it cascaded over them.13 Every ounce of amosite that reached an American shipyard or refinery was mined under conditions like these.

The government stockpile

The US government treated amosite as a strategic material. It classified amosite as critical before the war, restricted civilian use during the war, bought up the imported supply for military allocation, and then stockpiled tens of thousands of tons against future need. By the time the stockpile was put up for disposal in the 1990s, the world no longer wanted amosite, and for years the government could not find a buyer for roughly 30,000 metric tons of it. The stockpile was finally emptied around 2001.11

US consumption and the insulation concentration

The yearbooks also recorded where American amosite actually went. In 1973, total US amosite consumption was 4,273 short tons, and 84 percent of it (3,587 tons) went into insulation: pipe covering, block insulation, insulating cements, and blanket insulation for boilers, turbines, and industrial equipment. Construction uses such as spray fireproofing and asbestos-cement took about 6 percent, asphalt roofing felts about 7 percent, and miscellaneous uses the small remainder.11

That 84 percent is the most important number in the amosite record. By tonnage, amosite was a small share of American asbestos use: between 1900 and 2003 the United States imported about 282,000 metric tons of it, roughly 1 percent of all the asbestos it brought in, against about 98 percent for chrysotile.9 But tonnage understates the harm. The insulation trades that used most of the amosite were among the dustiest occupations in American industry, and amosite's long, straight fibers reach deep into lung tissue. So almost every mesothelioma case that traces to insulation work is, in significant part, an amosite case, though insulation usually contained chrysotile too, which makes amosite's role disproportionate rather than exclusive. The Selikoff cohort studies of the insulation workers' union, the studies that reshaped asbestos regulation in the 1960s and 1970s, were drawing on workforces whose main exposure was to amosite-containing insulation.11,14

US consumption had peaked far higher, at around 22,000 tons a year in the mid-1950s, and imports peaked in the late 1960s, with 14,580 tons entering the country in 1967 alone, almost all of it from South Africa. The 1973 total reflects a market already in steep decline as the first regulations and the first substitutes arrived.11

Fiber grades: the Penge system

Amosite was sold by fiber length, and because nearly all of it came from one place, the grading system was effectively the one used at the Penge mines in the Transvaal. Unlike the elaborate Quebec system used for chrysotile (which the chrysotile page covers in detail), the Penge grades were reported simply by length in inches, and amosite's narrower range of products, mostly thermal insulation and board, let the system stay simple.

The grades also changed over time. The earlier system, recorded by the US Bureau of Mines and in use until about 1952, ran from a long grade of 2 to 6 inches down through medium, short, and residue lengths:

Grade Length range Class
D3 2–6 in Long
D11 ½–2 in Medium
MD ½–2 in Medium
DX ½–2 in Medium
M ½–2 in Medium
K3 ½–2 in Medium
W3 ½–2 in Medium
WEG 0.12–3 in Medium
S2 0.18–1 in Shorts
SK 0.18–1 in Shorts
SW 0.18–1 in Shorts
R 0.12–0.5 in Residue
RK 0.12–0.5 in Residue
RW 0.12–0.5 in Residue

After about 1952, the producers stopped making the longest grades.15 By the time the system was set out in the industrial-minerals literature of the mid-1970s, the longest grade topped out near 1½ inches, and the grades had been tied more explicitly to the products they fed:

Penge grade Approx. fiber length Principal commercial use
S 11 1–1½ in Blanket insulation; woven textiles
W 3 ½–1½ in Woven insulation; specialty textiles
K 3 ½–1½ in Woven insulation; specialty textiles
SK 3/16–¾ in 85% magnesia pipe covering; Unibestos pipe insulation
S 33 ⅛–½ in Calcium-silicate reinforcement (Kaylo class)
S 33/66 ⅛–½ in Calcium-silicate reinforcement
GW ⅛–¼ in Structural board (Marinite class); acetylene cylinder reinforcement
GK ⅛–¼ in Structural board reinforcement
S 44 ⅛–¼ in Structural board; asbestos-cement filter aid
RK ⅛–¼ in Structural board; asbestos-cement filter aid
6605 1/16–⅛ in Filler applications

The later grades map onto the product names elsewhere on this page: the SK range went into 85 percent magnesia pipe covering and Unibestos pipe insulation, the S 33 range reinforced calcium-silicate insulation of the Kaylo class, and the GW range went into structural board of the Marinite class.16 Grade numbers were a shared vocabulary across the asbestos industry, but the product destinations were specific to each fiber. Where chrysotile of a comparable grade went mainly into asbestos-cement pipe, amosite of the SK range went into the high-temperature pipe insulation that chrysotile couldn't match on weight or heat.

One detail ties the grading back to the mine. Amosite preparation was, in the industry's own description, largely a matter of hand sorting, crushing, and screening, with the elaborate mill circuits of the chrysotile industry only partly adopted. The fiber-length distinctions in the grade tables were made, at least at first, by human hands. The women who cobbed raw fiber in the open air and the children who sorted and packed it in shipping bags, the conditions described above, were the grading process.13

Who was exposed to amosite

Amosite has more identifiable exposure pathways than any other asbestos fiber, because it was concentrated in specific products used by specific trades. You may have been exposed if you, or someone whose dusty work clothes you were around, fits one of these descriptions:

  • Served in the US Navy, especially in engine and boiler rooms (boiler technicians, machinist's mates, firemen, pipefitters, enginemen), or served in the merchant marine
  • Worked at a Navy or private shipyard as a pipe coverer, lagger, insulator, ship fitter, boilermaker, welder, electrician, or in a trade alongside them
  • Worked as an insulator or pipe coverer in any industry (this is the single most heavily exposed occupation in all of asbestos disease)
  • Worked at a power plant, oil refinery, chemical plant, or paper mill, or serviced one as a contractor
  • Worked as a boilermaker or pipefitter around steam systems
  • Installed, cut, repaired, or removed Kaylo, Unibestos, Marinite, or 85 percent magnesia insulation
  • Applied spray-on fireproofing, or did renovation or demolition in buildings that contain it
  • Worked at a plant that made amosite insulation products, such as the Unarco plant in Paterson, New Jersey (the plants our records name are listed below)

Family members were exposed too. Amosite fibers traveled home on work clothes, hair, and skin, and spouses and children have developed mesothelioma from that secondhand, or "take-home," exposure.

Health risks

All forms of asbestos cause the same group of diseases: asbestosis, mesothelioma, lung cancer, and cancers of the larynx and ovary.1 For how these diseases develop and what symptoms to watch for, see our page on asbestos-related diseases.

What sets amosite apart isn't which diseases it causes but how effectively it causes them. Three things combine to make it dangerous. Its fibers are long, straight, and rigid, so they reach deep into the lungs and pierce the lining where mesothelioma starts. They're highly durable, so they resist the body's efforts to clear them and stay embedded for decades. And they're rich in iron, which keeps the fiber chemically active in the tissue, driving the inflammation and DNA damage that lead to cancer.

The clearest proof of amosite's potency is the Paterson study described at the top of this page. Workers exposed for as little as a month died of lung cancer at nearly triple the expected rate, and among those who worked two years or more, 85 percent were dead within 35 years. The large studies of insulation workers that shaped the modern understanding of asbestos disease were drawing on workforces whose main exposure was to amosite insulation.14 Few asbestos exposures are as well documented, or as deadly.

Were you or a family member exposed to amosite?

If you've been diagnosed with mesothelioma, lung cancer, or asbestosis, and you think amosite may have been involved, we can help you find out whether you have a claim. That includes Navy service and shipyard work, the insulation trades, work in power plants, refineries, and chemical plants, exposure to specific products like Kaylo, Unibestos, and Marinite, and exposure brought home on a family member's clothes.

Many amosite products are covered by asbestos bankruptcy trusts, including trusts for Johns-Manville, Pittsburgh Corning (Unibestos), and the makers of Kaylo. That can mean compensation is available even when the original company no longer exists. You can learn more about filing an asbestos trust claim. If you're a Navy veteran, you may also have options through the VA in addition to a claim.

When you call, you reach our litigation team, not a screener. There's no fee unless we recover compensation for your family.

Call 833-4-ASBESTOS to speak with us about your case.

Is amosite still a danger today?

Amosite is one of the six minerals formally regulated as asbestos by the Environmental Protection Agency, the Occupational Safety and Health Administration, and the International Agency for Research on Cancer.1,17 The EPA's 2024 rule under the Toxic Substances Control Act banned the ongoing uses of chrysotile, the only asbestos type still imported and used in the country.18 In a separate 2024 evaluation, the agency assessed the other five fiber types, amosite among them, along with Libby amphibole and asbestos-containing talc, and found that asbestos poses an unreasonable risk to human health, with further regulation to follow.19 For where asbestos regulation stands now, see our main asbestos page.

Amosite mining ended worldwide in 1992, and no new amosite has been produced since. But the enormous amount installed over the previous decades is still out there. It remains in older Navy and merchant ships, in power plants and refineries, in industrial facilities, and in commercial buildings with sprayed fireproofing or old pipe insulation. Disturbing those materials during maintenance, renovation, or demolition releases the fibers, and because the disease can take decades to appear, new cases from past exposure will keep emerging for years.

Amosite in the industry's own words

The asbestos industry wrote about amosite for sixty years in its trade journal, Asbestos, and in the patents it filed. These are the articles and patents in our library that discuss it.

In the trade journal

The journal followed amosite from 1920, when it was a new fiber from South Africa, to the late 1960s, when articles were still recommending it for insulation, acoustical products and building materials. Each link opens the article's page in that issue.

In patents

113 US patents in our library mention amosite in their text, from a 1927 patent on preparing amosite for spinning into yarn to 1980. At least 23 were assigned to Johns-Manville. In 1943 Unarco was granted a patent on asbestos insulating yarn for weaving insulating blankets, filed in 1941, the kind of product the Paterson plant was built to make.

Every patent that mentions amosite (113), oldest first

Amosite mines in our records

The documents in our library report 6 mines producing amosite that was sold or shipped: the U.S. Bureau of Mines' and Geological Survey's yearbooks and the asbestos industry's trade journal, Asbestos. Each mine's page says who worked it and when, what it produced and which document says so.

  • Amosa (Pty.), Ltd. amosite operationSouth Africa · Amosa (Pty.), Ltd. · 1920–1961
  • Dublin Consolidated amosite facilitynear Pietersburg, Northern Transvaal, Transvaal · Dublin Consolidated Asbestos Mines (Pty.) Ltd., Turner & Newall Ltd., S. A. Kirton (Pty) Ltd. (tributer) · 1975–1978
  • Kromellenboog mineLydenburg District, Transvaal · Egnep (Pty.) Ltd., Cape Industries Ltd., Egnep, Limited · 1945–1977
  • Malips Drift (McBean's) minenear Malips River, Transvaal · Malips Drift Asbestos Mines Limited, Cape Asbestos Company Limited, Cape Blue Mines (Pty) Ltd. and others · 1913–1959
  • Penge minePenge, Transvaal · Egnep, Ltd., Cape Asbestos S.A. (Pty.), Ltd. · 1914–1980
  • South African Consolidated Asbestosa few miles from the Montana Mine, Transvaal · South African Consolidated Asbestos Limited · 1928–1929

Our records also name 6 other amosite deposits and mines with no reported sales.

Plants that made amosite products

Companies' sworn answers in asbestos lawsuits, the asbestos industry's trade journal and company records in our library name 87 asbestos products as containing amosite, made at 26 plants. Many of these products contained other fibers too; each product's page gives what each document says it contained. People who worked in these plants, their families, and people who lived nearby may have been exposed.

Every asbestos product plant, by state and city

References

  1. IARC. Arsenic, Metals, Fibres, and Dusts. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol 100C. International Agency for Research on Cancer; 2012.
  2. Roemer CH. Deposition of Charles H. Roemer. In re Johns-Manville Corp. US Bankruptcy Court; April 25, 1984. See also Affidavit of Charles H. Roemer, September 29, 1982.
  3. Seidman H, Selikoff IJ, Hammond EC. Short-term asbestos work exposure and long-term observation. Ann N Y Acad Sci. 1979;330:61-89.
  4. Ross M. The geological occurrences and health hazards of amphibole and serpentine asbestos. In: Veblen DR, ed. Amphiboles and Other Hydrous Pyriboles — Mineralogy. Reviews in Mineralogy. Vol 9A. Mineralogical Society of America; 1981:279-323.
  5. Hall AL. Asbestos in the Union of South Africa. Memoir No. 12. Department of Mines and Industries, Union of South Africa; 1918.
  6. Dana ES, Dana JD. Dana's New Mineralogy. 8th ed. Wiley; 1997.
  7. Gruner EL. Original description of the grunerite mineral specimen. 1847.
  8. Kenngott A. Das Mohs'sche Mineralsystem. 1863. [Named the mineral grunerite in honor of E.L. Gruner.]
  9. Virta RL. Worldwide Asbestos Supply and Consumption Trends From 1900 to 2003. US Geological Survey Circular 1298. US Department of the Interior; 2006.
  10. Fleischer WE, Viles FJ, Gade RL, Drinker P. A health survey of pipe covering operations in constructing naval vessels. J Ind Hyg Toxicol. 1946;28(1):9-16.
  11. US Geological Survey. Minerals Yearbook: Asbestos [annual chapters]. US Department of the Interior; 1932-2024.
  12. McCulloch J. Asbestos Blues: Labour, Capital, Physicians and the State in South Africa. James Currey Publishers; 2003.
  13. Schepers GWH. Report on Conditions at Penge Mine. 1965. Testimony regarding working conditions at South African amosite mines, originally reported to the South African Department of Mines, 1949.
  14. Selikoff IJ, Lee DHK. Asbestos and Disease. Academic Press; 1978.
  15. Bowles O. Asbestos: A Materials Survey. Information Circular 7880. US Bureau of Mines; 1959:25. (Revised edition; originally issued 1952.)
  16. Industrial Minerals and Rocks. 4th ed. American Institute of Mining, Metallurgical, and Petroleum Engineers; 1975:476.
  17. Occupational Safety and Health Administration. Asbestos. 29 C.F.R. § 1910.1001.
  18. US Environmental Protection Agency. Asbestos Part 1; chrysotile asbestos; regulation of certain conditions of use under the Toxic Substances Control Act (TSCA). Fed Regist. 2024;89(61):21970-22010.
  19. US Environmental Protection Agency. Risk Evaluation for Asbestos, Part 2: Supplemental Evaluation Including Legacy Uses and Associated Disposals of Asbestos. US Environmental Protection Agency; 2024.

Key Sources

Cape Asbestos Company Limited. Amosite Asbestos [advertisement]. Cape Asbestos Company; 1938.

"In Memoriam: Robert E. Cryor." Asbestos. May 1970:14.

Badollet MS. Asbestos, a mineral of unparalleled properties. Transactions of the Canadian Institute of Mining and Metallurgy. 1951;54:151-160.

Speil S, Leineweber JP. Asbestos minerals in modern technology. Environ Res. 1969;2(3):166-208.

In the research library

The National Library of Medicine indexes 235 studies in our medical research library under amosite. Among the most cited:

See all 235 studies on amosite

In our case-law library

49 court decisions in our case-law library involve amosite. Among them:

See all 49 decisions involving amosite

Frequently asked questions

Is amosite asbestos?

Yes. Amosite is one of the six minerals regulated as asbestos under US law. It's part of the amphibole group, along with crocidolite, anthophyllite, tremolite, and actinolite.

What is brown asbestos?

Brown asbestos is the common name for amosite. The brown color comes from the iron in the mineral. It's also the fibrous form of a mineral called grunerite.

Where did amosite come from?

Only from the Transvaal region of South Africa, the one place on Earth it was mined commercially. The name comes from "Amosa," short for Asbestos Mines of South Africa.

What products contained amosite?

Almost all amosite went into high-temperature insulation: 85 percent magnesia pipe and block insulation, Unibestos pipe insulation, Kaylo, Marinite board, and spray-on fireproofing, plus smaller uses in asbestos-cement and roofing products.

Were Navy ships insulated with amosite?

Yes. The Navy specified amosite for shipboard insulation for decades because it was lighter than the alternatives while handling the same heat. Shipyard workers and sailors who served in engine and boiler rooms were heavily exposed.

Why is amosite considered especially dangerous?

Its fibers are long, rigid, and durable enough to lodge deep in the lungs and stay for decades, and its high iron content keeps the fiber chemically active in the tissue. Studies of amosite workers found very high rates of mesothelioma and lung cancer, even after short exposures.

Can a short exposure to amosite cause cancer?

Yes. In the Paterson worker study, men exposed for as little as one month died of lung cancer at nearly triple the expected rate. You do not need years of exposure.

What should I do if I think I was exposed?

If you've been diagnosed with an asbestos-related disease and think amosite may have been involved, call 833-4-ASBESTOS. You'll reach our litigation team, and there's no fee unless we recover compensation for your family.

Talk with an asbestos lawyer

Start with what you remember, and we'll take it from there.

Call 833-4-ASBESTOS Request a free case review

This page is provided for general informational purposes and does not constitute legal advice. Every asbestos case turns on its own facts, exposure history, diagnosis, deadlines, available evidence, and applicable law. Reviewing this page does not create an attorney-client relationship. For advice about your specific situation, call 833-4-ASBESTOS for a free case review.