There are six recognised types of asbestos, divided into two mineralogical groups. Three of them — chrysotile, amosite, and crocidolite — were used commercially on a large scale and account for almost all the asbestos you'll encounter in UK buildings. The other three — tremolite, actinolite, and anthophyllite — were used in small specialist applications and more often appear as natural contaminants of other minerals like talc and vermiculite.
All six are classified as Group 1 carcinogens by the International Agency for Research on Cancer. There is no version of asbestos that is safe; the differences between the types affect how readily they release fibres and how those fibres behave in the body, but they don't change the underlying classification.
This guide walks through each type — fibre shape, typical uses in the UK, when it was banned — and explains why the colour names you've probably heard are an unreliable way to identify what you're actually looking at.
The two mineral groups
The first thing to understand is that asbestos isn't a single substance. It's a generic commercial term for a group of naturally occurring silicate minerals that share two characteristics: they're fibrous in form, and the fibres are durable enough to survive heating, chemical attack, and mechanical stress.
The six types split into two mineral groups based on their crystal structure:
- Serpentine asbestos — only chrysotile. Curly, soft fibres that can be spun and woven.
- Amphibole asbestos — amosite, crocidolite, tremolite, actinolite, and anthophyllite. Straight, stiff, needle-like fibres that don't bend.
The fibre types differ in their biological behaviour, but all six are carcinogenic. Assess the material, condition and planned work rather than treating any fibre type as safe.
Chrysotile (white asbestos)
Chrysotile was widely used in asbestos cement, flooring and other products. Building stock contains different materials and mixtures; analysis is needed to identify the type in a particular product.
- Mineral group: Serpentine
- Mineralogical name: Chrysotile (Mg₃Si₂O₅(OH)₄)
- Fibre shape: Curly, soft, flexible — can be spun like cotton
- Colour in raw form: Pale grey-white to grey-green
- Main chrysotile prohibition: Great Britain, 24 November 1999; Northern Ireland, 2 May 2000
Chrysotile's softness and flexibility made it the most versatile of the asbestos minerals. It could be spun, woven, mixed into cement, bonded into vinyl, and applied as a sprayed coating. The UK's heaviest historical uses included:
- Asbestos cement (roof sheets, gutters, downpipes, water tanks, flues)
- Vinyl and thermoplastic floor tiles
- Textured coatings on walls and ceilings (Artex being the most familiar brand)
- Rope seals and gaskets in stoves, boilers, and ovens
- Pipe lagging (often alongside amosite)
- Brake linings, clutch plates, and other automotive friction materials
- Insulation in domestic boilers and electrical equipment
Chrysotile-containing materials can remain in older buildings, including products installed late in the twentieth century. Dates and appearance alone cannot confirm the composition.
Amosite (brown asbestos)
Amosite was the second most heavily used asbestos in UK construction, particularly in mid-to-late twentieth century commercial buildings.
- Mineral group: Amphibole
- Mineralogical name: Grunerite ((Fe,Mg)₇Si₈O₂₂(OH)₂)
- Fibre shape: Straight, harsh, brittle, needle-like
- Colour in raw form: Grey-brown to dull brown, sometimes greenish
- Blue/brown prohibition: Great Britain, 1 January 1986 under the 1985 regulations; Northern Ireland, 6 March 1986
Amosite is commonly called brown asbestos and is the asbestos form of the mineral grunerite. Its name or apparent colour cannot identify it in a building material; identification requires appropriate analysis.
Amosite's combination of straight, brittle fibres and excellent heat resistance made it the asbestos of choice for:
- Asbestos insulating board (AIB) — ceiling tiles, wall panels, partition boards, fire-door linings
- Pipe lagging (often blended with chrysotile)
- Sprayed coatings on structural steel, particularly for fire protection
- Thermal insulation around boilers and calorifiers
Of all the asbestos types you'll find in a UK building, amosite is the one most associated with AIB — and AIB is one of the most encountered hazardous materials in commercial property refurbishments. Amosite is also strongly associated with mesothelioma; the disease burden among workers who installed and stripped out AIB through the 1960s and 70s is part of the reason brown asbestos was banned a decade and a half before chrysotile.
Crocidolite (blue asbestos)
Crocidolite is a hazardous amphibole asbestos associated with serious disease. Identifying it requires analysis; neither the colour name nor a simple danger ranking decides the controls for a task.
- Mineral group: Amphibole
- Mineralogical name: Riebeckite, fibrous form (Na₂(Fe,Mg)₅Si₈O₂₂(OH)₂)
- Fibre shape: Very thin, straight, sharp needles
- Colour in raw form: Distinct grey-blue
- Blue/brown prohibition: Great Britain, 1 January 1986; Northern Ireland, 6 March 1986
Crocidolite’s association with mesothelioma was documented before the statutory prohibitions. Historical use patterns help explain where it may be found, but cannot establish a particular product’s composition.
Crocidolite appeared in:
- Sprayed coatings on structural steel in commercial buildings, primarily 1950s and 60s
- Specialist pipe lagging, particularly in marine and industrial settings
- Cement products in some 1950s manufacturing
- Loose-fill insulation in a small number of buildings
- Asbestos-woven textiles and high-temperature gaskets
- Marine and shipbuilding insulation, where crocidolite use was extensive
Older commercial and industrial buildings may contain crocidolite products. Use competent assessment and the precautions required by the actual material and task, rather than assume an early use date makes disturbance unlikely.
Tremolite, actinolite, and anthophyllite
These three amphibole minerals were used commercially in only limited quantities — and where they do appear, it's often as contaminants of other materials rather than as deliberately added asbestos.
Tremolite is an amphibole mineral. Its asbestiform variety can occur as a contaminant in other mineral deposits, including some talc and vermiculite. The name of the host material alone does not confirm contamination.
Actinolite is an amphibole mineral; its asbestiform variety is included in the asbestos regulations. It can occur with other minerals, so analysis matters more than colour or product name.
Anthophyllite ((Mg,Fe)₇Si₈O₂₂(OH)₂) is a yellow-brown amphibole that saw some specialist use in insulation and construction materials in the mid-twentieth century, though much less than the three main commercial types.
All three are covered by the same regulatory framework as the commercial asbestos types. If they're identified in a sample during analysis, they're treated as asbestos for the purposes of management, disposal, and licensing.
All six at a glance
The six types and their main characteristics are summarised below. The prohibition dates given here refer to Great Britain:
- Chrysotile — serpentine asbestos with curly fibres; used in cement, flooring and other products. Main GB prohibition: 24 November 1999.
- Amosite — amphibole asbestos; associated with insulating board and thermal insulation. GB prohibition: 1 January 1986.
- Crocidolite — amphibole asbestos; used in coatings, insulation and some cement products. GB prohibition: 1 January 1986.
- Tremolite — its asbestiform variety is regulated asbestos and can occur as contamination in other minerals. GB prohibition: 1 January 1993.
- Actinolite — its asbestiform variety is regulated asbestos, sometimes found with other minerals. GB prohibition: 1 January 1993.
- Anthophyllite — amphibole asbestos with limited historic uses. GB prohibition: 1 January 1993.
The GB restrictions developed in more than two stages: blue and brown asbestos from 1986, the other amphiboles from 1993, and chrysotile from November 1999. The historical 2006 consolidation records these separate dates for products already in use.
Which type is most dangerous?
This is the question every page on the topic answers slightly differently, and the honest answer requires nuance.
The IARC classifies all six asbestos types as Group 1 carcinogens — known to cause cancer in humans. No type is safe at any exposure level. The "no safe threshold" principle applies to all of them.
The practical assessment must consider:
- The fibre type, where known from reliable analysis
- How readily the product can release fibres, its condition and surface treatment
- The work method, likely exposure, duration and effective controls; no type is a safe alternative to another
The practical implication is that "which is worst" matters less than "how much, for how long, and in what condition". A friable, damaged amosite ceiling tile being broken up with a hammer is a very different hazard from intact chrysotile-bonded cement on a stable garage roof. Both are asbestos; both are regulated; but the work activity and material condition drive the actual risk profile.
Why colour identification is unreliable
The colour names — white, brown, blue — refer to the appearance of the raw mineral fibre in mined form. Once asbestos is bound into a building product, the original colour is no longer visible. A chrysotile-containing cement sheet is grey, the colour of cement. A textured ceiling coating with chrysotile in it is whatever colour the householder painted it. A floor tile with amosite is the colour the manufacturer designed.
This is the most common misconception in DIY asbestos identification: that you can spot which type you're dealing with by what colour the material is. You can't. The only reliable way to identify the type is laboratory analysis, typically polarised light microscopy on a small physical sample at a UKAS-accredited lab.
Even within raw asbestos, colour is variable. Chrysotile ranges from white to grey-green depending on the deposit. Crocidolite can look more grey than blue in some lighting. Amosite varies from grey-brown to almost greenish. The colour names are a useful shorthand for someone who already knows the mineralogy; they're not a field identification tool.
Frequently asked questions
Are all six types of asbestos equally dangerous?
The types differ, but all are carcinogenic. The material’s condition, potential fibre release and task also affect risk, so a simple ranking cannot establish the controls or licensing category.
Was blue asbestos banned before white?
Yes. In Great Britain, the blue/brown prohibition took effect on 1 January 1986, while the main chrysotile prohibition took effect on 24 November 1999. Northern Ireland’s corresponding dates were 6 March 1986 and 2 May 2000.
Why was chrysotile considered safer?
Differences in fibre properties were part of historical debates, but chrysotile is carcinogenic and can cause serious disease. Do not use “white asbestos” as a reason to relax controls.
What's the difference between amosite and crocidolite?
Both are amphibole asbestos, but they are different minerals: amosite is associated with grunerite and crocidolite with riebeckite. Their colour names are descriptive of raw material, not a reliable test for building products.
Are tremolite and actinolite ever found in UK homes?
Asbestiform tremolite or actinolite can occur as contaminants in other materials. A product’s name or origin does not establish its contents; use appropriate analysis when identification is needed.
Can you identify the type of asbestos by colour alone?
No. The colour names refer to the raw mineral, which you'll almost never see in a building. Once asbestos is bound into cement, board, vinyl, or paint, the original colour is gone. Laboratory analysis is the only reliable identification method.
For a deeper look at what these materials actually look like in UK buildings, see our visual reference for recognising asbestos. For the legal framework that now governs all six types and the buildings they're in, see the Control of Asbestos Regulations 2012. For the historical context of how and when each type was prohibited, our UK asbestos ban timeline walks through the legislation. And for tradespeople and supervisors who could foreseeably disturb any of these asbestos types in their work, our Asbestos Awareness Course covers the training required under Regulation 10.
The HSE's general guidance on asbestos provides the official regulatory reference for all six types.
Related guides
- Types of asbestos surveys: management, refurbishment, and demolition explained
- The duty to manage asbestos: registers, plans, and what Regulation 4 requires
- Asbestos-containing materials in UK buildings: a reference guide
Sources & references
- UKHSA — asbestos types and properties
- WHO — all asbestos forms are carcinogenic
- HSE — asbestos materials and analysis
- Historical GB regulations — prohibition dates in regulation 29
- Northern Ireland — blue/brown prohibition
- Northern Ireland — chrysotile prohibition
Need Category A asbestos awareness training for yourself or your team?
Explore the Asbestos Awareness Course →
Mark writes about workplace health & safety, asbestos awareness and accredited online training for Asbestos Awareness Course, part of Online CPD Academy.