The 6 Types Of Asbestos That The U.S Regulates

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The 6 types of Asbestos the US Regulations

With Mesothelioma on the news and government agencies enforcing asbestos inspections, it is becoming safe to say that Asbestos is starting to become a common word. The chances are that if you stumbled onto this article, you’ve heard it several times already. One problem though is aside from the medical fears of mesothelioma and lung cancer; little is known about asbestos. In fact, most people don’t realize that asbestos isn’t a specific rock or mineral but instead a classification of several minerals that share similar characteristics. That being said, there are six types of asbestos minerals that are heavily regulated by US government agencies such as OSHA and EPA.

Asbestos is a classification of certain minerals that are found throughout the world. Asbestos is distinguishable from other minerals in that its crystals form long, thin fibers. These fibrous crystal habits are known as asbestiform. This structure allows the asbestos to have soft and flexible properties as well as its ability to withstand heat. They are extremely flexible with a relatively small diameter and a large length. With these general characteristics, they’re individual characteristics for each mineral considered as asbestos.

Asbestos minerals are divided into two groups, Serpentine, and Amphibole.


Chrysotile Asbestos - A Serpentine Mineral
Chrysotile Asbestos – A Serpentine Mineral


The serpentine group describes a group of common rock-forming hydrous magnesium iron phyllosilicate ((Mg, Fe)3Si2O5(OH)4) minerals. Other elements may be added, but they each contain that specific chemical compound. Serpentine minerals are also known for its sheet/layered crystalline structure. The only asbestos mineral that exists in the Serpentine Group is Chrysotile.
Fun Fact: The Serpentine rock is the California state rock. (don’t worry not all serpentine contain asbestos)



Chrysotile is the only asbestiform found in the serpentine group. Chrysotile accounts for 95% of the asbestos found in buildings in the United States. It is also the most common asbestos found in outside air assessment. This leads Chrysotile to be the most known form of Asbestos.
Chrysotile, also known as white asbestos, have several key features that separate it from the other 5 regulated asbestiform. Due to its sheet-like structure, being in the Serpentine group, it wets easily. This is good news as merely wetting Chrysotile can help prevent it from going airborne, which is when it is the most dangerous. Chrysotile was found in Gaskets, Insulation, Brake Pads, Brake Linings, Roofing Materials, and Joint Compound. Chrysotile was most commonly used in sprayed-on fireproofing. It comprised of 5-95 percent of the fireproofing mixture and was used in conjunction with materials such as vermiculite and cellulose fibers.

Anthophyllite Asbestos - Amphibole Asbestos
Anthophyllite Asbestos – Amphibole Asbestos


Amphibole covers a diverse group of minerals. They can be classified based on their crystallized structure, and their chemical structure. For asbestos identification, amphibole’s can be classified based on their needlelike crystal appearance. They’re five types of asbestos the U.S are concerned with that fall within this group; Amosite, Crocidolite, Tremolite, Anthophyllite, and Actinolite.



Amosite can be considered as the second most hazardous type of asbestos. It is the fibrous asbestiform of the mineral grunerite, an Amphibole mineral. Also known as brown asbestos, Amosite consisted around 5% of the asbestos used in building materials. Unlike Chrysotile, Amosite was a water repellant. To properly wet Amosite, a surfactant was required. It was most commonly found in environments of extreme heat due to its high heat stability. Some of the common items include Cement Sheets, Thermal Insulation, Plumbing Insulation, Tiles, Chemical Insulation, Roofing Products, and Fire Protection.



Crocidolite, also known as the blue asbestos, is the 3rd most common form of Asbestos. Crocidolite is the asbestiform habit of riebeckite. It didn’t have the same heat resistance as the other asbestos but was more commonly used for its chemical resistance. Crocidolite was often found in Chemical Insulation, Spray-on insulation, Acid storage battery casings, or Water encasement.



Tremolite is one of the uncommon asbestos found in homes. Still considered as one of the six that are regulated by the United States, Tremolite isn’t as much of a concern as Chrysotile, Amosite or Crocidolite. It may sound funny to say that one of the six heavily regulated minerals isn’t a concern, but that’s because of how uncommon it is in the industry. It wasn’t mined on purpose or meant to be used commercially. Instead, it was a contaminant in Chrysotile and has been found in building materials as a result.
It is also noted that not all Tremolite is an asbestiform as it can exist in a non-asbestiform state. This is also the case as Anthophyllite and Actinolite. Still, there is still a chance of it being found in a home, and for it to be asbestiform. As one of the six regulated asbestos, we treat it and respond to it the same way we would react to any of the other asbestos.



Similar to Tremolite, Anthophyllite is rarely found in large quantities. Usually, the presence of Anthophyllite is due to contamination and is commonly found in trace quantities. Not all anthophyllite are asbestiform as it can exist as a non-asbestiform. This is determined on whether the structure has a fibrous appearance. Whether or not it is asbestiform or not, Anthophyllite is still treated as a hazard. Anthophyllite can be found in Talc and Vermiculite



Actinolite has rarely been used and can be considered uncommon since asbestos was deemed dangerous. None the less, it can still be found in older buildings before the regulations in the 1970s. Actinolite is an Amphibole mineral and similar to Tremolite and Anthophyllite, can be asbestiform or non-asbestiform. As a precaution, the presence of fibrous Actinolite should still be treated like all the other asbestos. It isn’t uncommon to discover actinolite in rocks or soil, which isn’t a problem as long as it isn’t being damaged (drilling and blasting). Actinolite can be found as a contaminant in Talc.



There are six different types of asbestiform which make up Asbestos. As a professional, it is important to identify accurately which type of asbestos is present as the removal process will be different for each type. As a consumer, understanding that not all asbestos are made the same may clear some things up when trying to understand why your asbestos removal may be different from the one your neighbor had. There has been some research on each type of asbestos having different dose related exposure or the amount of a specific asbestos to make you sick, but it is considered best practice to treat them all as an environmental hazard. No matter which form of asbestos you may find, always seek a professional for guidance and assistance.