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Tremolite, Anthophyllite and Actinolite asbestos

These three forms of asbestos may be less familiar, but still pose a significant danger to health if their fibres are inhaled. They weren’t used as prolifically in industry as crocidolite, amosite and chrysotile, but are still present in many insulating and fireproofing materials.


Tremolite (Calcium Magnesium Silicate Hydroxide) is part of the amphibole class of asbestos, and has needle-like fibres that are extremely difficult to expel from the body. Commonly a constituent part of other minerals including vermiculite, talc, and chrysotile asbestos, tremolite can occur in shades of green, grey, white or brown.

Tremolite was mined only in a few places globally, and in small amounts, and products containing the substance are not often seen in this country. It is thought to be as dangerous as other forms of asbestos, however, if handled incorrectly.

Where might you come across tremolite?

Although its use was not as widespread in industry as blue, white, and brown asbestos, tremolite’s insulating properties made it useful in some construction materials. It may be found in:

  • Asbestos insulating board (AIB)
  • Asbestos cement sheeting and pipes
  • Casings for telecoms and electrical wiring
  • Thermal insulation, such as lagging
  • Fire doors
  • Gaskets
  • Vermiculite products such as loft insulation, whitewashes and packaging materials
  • Talc products, including ceramics and chalks
  • Paint and sealant


Anthophyllite is a magnesium and iron silicate that is fibrous in nature, and also very brittle. It is generally brown in colour, but various other shades may be present, including green, grey and yellow.

As a member of the amphibole class, anthophyllite fibres are needle-like in appearance but unlike crocidolite and amosite, they have low tensile strength and for this reason did not have the same value to industry.

Anthophyllite can be found in various areas of America including Pennsylvania and Montana, and also in Asia and Northern Europe – Finland in particular.

How was anthophyllite used?

It can be found in the vermiculite products mentioned above and historically, also in cosmetic talcum powders. Uses include the manufacture of building materials due to its insulating and fireproofing properties. These include:

  • Asbestos cement
  • Composite flooring
  • Insulation
  • Roofing material
  • Paints and sealants


Actinolite is similar in nature to tremolite, but less commonly used. Although having an identical crystal structure, actinolite contains more iron but less magnesium than tremolite. It was mined in several areas around the world, including Australia and North Caroline, USA.

Which products might contain actinolite?

This substance was generally included in insulation and fireproofing materials, along with other minerals, and is generally brown, grey or green in colour. Older residential and commercial buildings may still contain products manufactured with actinolite, as it provided a lightweight insulating solution in the building trade.

Its uses included:

  • Concrete materials
  • Sealants and paints
  • Horticultural vermiculite

All three of these forms of asbestos have the potential to cause life-threatening disease if they are inhaled or ingested by the body. Asbestos awareness training covers all six forms of asbestos, so you’ll know where they might occur and what they look like.

Further Reading

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