Is serpentine asbestos?
Not as a group: serpentine is three IMA species with one formula, and UK law names one, chrysotile, as asbestos. HSE lists the other two apart. Not advice.
Not as a group. Serpentine is not an IMA species: three species share its formula, Mg3Si2O5(OH)4, and regulation 2 of the UK Control of Asbestos Regulations 2012 names one, chrysotile (CAS No 12001-29-5), as asbestos. HSE’s analysts’ guide lists the other two, lizardite and antigorite, as chrysotile’s non-asbestos analogues. This is not safety advice.
In short
- What the law names. The Control of Asbestos Regulations 2012, regulation 2, read on legislation.gov.uk on 10 November 2026 in its latest available revised form, says asbestos means the following fibrous silicates: (a) asbestos actinolite, (b) asbestos grunerite (amosite), (c) asbestos anthophyllite, (d) chrysotile, CAS No 12001-29-5 or CAS No 132207-32-0, (e) crocidolite and (f) asbestos tremolite. The word serpentine is not in the definition; chrysotile is.
- The one-of-three rule. A script over the September 2026 IMA-CNMNC Master List finds no serpentine row and exactly three rows printing Mg3Si2O5(OH)4: antigorite, chrysotile and lizardite. HSE’s HSG248, Asbestos: The Analysts’ Guide, Table A2.1, lists chrysotile as the regulated asbestos variety of the serpentine group and gives lizardite and antigorite as its non-asbestos mineral analogues; USGS’s Virta (2002) says the serpentine group contains a single asbestiform variety, chrysotile. One of the three is named; two are listed apart from it.
- Documented failure: the 1.5 ledger. All three species share one formula, and the sheets’ ideal columns for clinochrysotile and antigorite are the same: SiO2 43.37, MgO 43.63, H2O 13.00. Worked from the five real analyses on the four Handbook of Mineralogy sheets, Mg/Si is 1.473 for the chrysotile, 1.470 and 1.392 for antigorite, and 1.361 and 1.451 for lizardite, against 1.500 ideal. A chemical analysis does not pick chrysotile out.
- Documented failure: fibrous. The clinochrysotile sheet prints asbestiform, fibrous along [100], curled to cylindrical. But the antigorite sheet also prints commonly bladed or fibrous, while USGS calls antigorite a nonfibrous variety of serpentine and HSE lists it as non-asbestos. The word fibrous on a label, or on a sheet, does not decide which species a piece is. HSE’s guide describes that identification as polarised light microscopy in a laboratory.
- No verdict here. This page does not say any serpentine, serpentinite or specimen is or is not hazardous. Questions go to HSE’s asbestos pages, an asbestos surveyor or analyst, and a clinician. This is not health, safety or legal advice.
| IMA species | IMA status, year, country | Named in regulation 2? | HSG248 Table A2.1 | Handbook sheet | Habit words as printed | Hardness | Density | Mg/Si of sheet analysis |
|---|---|---|---|---|---|---|---|---|
| Chrysotile | Rd, 2007 s.p., Poland | Yes: (d) chrysotile, CAS No 12001-29-5 or 132207-32-0 | Asbestos variety, serpentine group | Clinochrysotile (“chrysotile-2Mc1”) | Asbestiform, fibrous along [100], curled to cylindrical; also bladed, massive | 2.5 | 2.53 meas., 2.61 calc. | 1.473 (Joe No. 5 pit, California) |
| Chrysotile | Same IMA row | Yes | Asbestos variety | Orthochrysotile (“chrysotile-2Orc1”) | Fibrous along [100]; asbestiform | 2.5 | [2.58] calc. | No analysis: the sheet says positively known material apparently has not been analyzed |
| Antigorite | Rd, 1998 s.p., Italy / Switzerland | Not named | Non-asbestos mineral analogue | Antigorite | Minute crystals, typically platy along [001]; commonly bladed or fibrous | 2.5–3.5 | 2.65 meas., 2.61 calc. | 1.470 (Unst, Scotland); 1.392 (Maryland) |
| Lizardite | G, 1956, United Kingdom | Not named | Non-asbestos mineral analogue | Lizardite | Crystals rare, to 2 mm, as trigonal plates; commonly extremely fine-grained scales and massive aggregates | 2.5 | 2.55 meas., 2.57 calc. | 1.361 (Kennack Cove, Cornwall); 1.451 (Coli, Italy) |
Is serpentine asbestos? What regulation 2 names
UK law names chrysotile, not serpentine. Regulation 2 of the Control of Asbestos Regulations 2012, read on legislation.gov.uk on 10 November 2026 in its latest available revised form, says: asbestos means the following fibrous silicates, and lists (a) asbestos actinolite, CAS No 77536-66-4; (b) asbestos grunerite (amosite), CAS No 12172-73-5; (c) asbestos anthophyllite, CAS No 77536-67-5; (d) chrysotile, CAS No 12001-29-5 or CAS No 132207-32-0; (e) crocidolite, CAS No 12001-28-4; and (f) asbestos tremolite, CAS No 77536-68-6. A script finds the string serpentin nowhere on the regulation’s page and chrysotile twice, the second time in the definition of asbestos cement.
Serpentine is a group, not a species. The September 2026 IMA list has no serpentine row, by script; the four Handbook sheets for the serpentine minerals all print Kaolinite-serpentine group, and HSE’s HSG248, Asbestos: The Analysts’ Guide, paragraph A2.2, says chrysotile is classified as a sheet silicate and is a member of the serpentine group. So the question is which serpentine species a piece is. is serpentine jade covers the same three species for the jade question and is not repeated here.
Not repeated here. The name test and fibrous-habit survey are on is scolecite asbestos; the tensile-strength and dispersion-staining points on is tremolite asbestos; the CAS pair and fibre-ratio points on is actinolite asbestos; the two-family check and seven-sheet ledger on is okenite asbestos; the crocidolite name check on is tiger’s eye asbestos.
Which serpentine is chrysotile? The one-of-three rule
Of the three species that share the serpentine formula, one is named in regulation 2 and the other two are listed by HSE as its non-asbestos analogues. By script, the September 2026 IMA-CNMNC Master List has exactly three rows printing Mg3Si2O5(OH)4: antigorite (Rd, 1998 s.p.), chrysotile (Rd, 2007 s.p., Poland) and lizardite (G, 1956, United Kingdom). No row is named clinochrysotile, orthochrysotile or parachrysotile. HSG248’s Table A2.1, of regulated asbestos varieties and their non-asbestiform mineral analogues, puts chrysotile, 12001-29-5, under the serpentine group with lizardite and antigorite as its non-asbestos mineral analogues and Mg3(Si2O5)(OH)4 as the nominal composition.
USGS says the same from the mineral side. Virta, Asbestos: Geology, Mineralogy, Mining, and Uses, USGS Open-File Report 02-149 (2002) writes that asbestos fibres belong to two mineral groups, serpentines and amphiboles, and that the serpentine group contains a single asbestiform variety: chrysotile. Its Table 1 gives chrysotile’s other designation as white asbestos and footnotes that chrysotile is in the serpentine mineral group, all the others amphiboles.
How the Handbook splits chrysotile. The Handbook has no unsuffixed chrysotile sheet. Its clinochrysotile sheet says the mineral may also be termed chrysotile-2Mc1, and its orthochrysotile sheet says chrysotile-2Orc1; each lists antigorite, lizardite, the other chrysotile and parachrysotile as polymorphs. Both describe the habit as fibrous along [100] and asbestiform. A label reading clinochrysotile or orthochrysotile names chrysotile.
Can an analysis tell chrysotile from antigorite? The 1.5 ledger
No: the three species have one formula, and real analyses of each scatter across the same range. The clinochrysotile sheet’s ideal column and the antigorite sheet’s are identical, SiO2 43.37, MgO 43.63, H2O 13.00, which is Mg3Si2O5(OH)4 worked on standard atomic weights (43.36, 43.63, 13.00). USGS’s Virta (2002) calls antigorite’s chemical composition nearly identical to that of chrysotile.
Worked on the sheets. Mg/Si, as moles from the printed MgO and SiO2, is 1.473 for the clinochrysotile analysis from the Joe No. 5 pit, California; 1.470 for antigorite from the Nikka Vord quarries, Unst, Scotland, and 1.392 from the State Line pits, Maryland; and 1.361 for lizardite from Kennack Cove, Cornwall, and 1.451 from Coli, Italy. The formula gives 1.500. The chrysotile and the Unst antigorite differ by 0.003, while the two lizardites differ from each other by 0.090. The orthochrysotile sheet adds that material positively known to be that species apparently has not been analyzed.
What decides it, then. Structure and habit, examined by a laboratory. HSG248 describes fibres being positively identified as one of the six regulated types on their detailed optical properties by polarised light microscopy. That is analysts’ work, and this page offers no by-eye or bench substitute for it.
Fibrous is not the test: the antigorite conflict
A sheet can print fibrous for a species that HSE and USGS place outside asbestos. The antigorite sheet describes minute crystals, typically platy along [001], rarely elongated along [010], with some plates rectangular in outline from cleavage, commonly bladed or fibrous; its lustre runs resinous, greasy, silky, waxy or earthy. USGS’s Virta (2002), describing a photograph of cross-vein chrysotile, calls antigorite a nonfibrous variety of serpentine, and HSG248 lists antigorite as a non-asbestos analogue. The two sources use the habit word differently; the law names a species, chrysotile, not a habit.
Lizardite. The lizardite sheet records crystals rare, to 2 mm, as trigonal plates to truncated trigonal pyramids, commonly as extremely fine-grained scales and massive aggregates, waxy in lustre, and calls it probably the most common serpentine mineral. It prints no fibrous habit. The sheet names it for its type locality, the Lizard complex, Cornwall. Lizardite is not named in regulation 2.
The lesson for a label. Fibrous, silky or asbestiform on a label describes a look. Platy or massive does not rule chrysotile out of a piece either, since the clinochrysotile sheet also prints bladed and massive habits and its occurrence is intermixed with orthochrysotile in veinlets. Only identification says which species is there.
Is serpentine rock dangerous? What the sources record
This page does not answer that; it reports where the sources place chrysotile. The clinochrysotile sheet gives its occurrence as intermixed with orthochrysotile in veinlets cutting serpentinite, and the orthochrysotile sheet the same. USGS’s Virta (2002) says chrysotile fibres are found as veins in serpentines, in serpentinized ultramafic rocks and in serpentinized dolomitic marbles, and that chrysotile accounts for only a small percentage of the minerals found in these rock types. HSG248, paragraph A2.2, says rocks containing serpentine and amphiboles occur widely on the earth’s surface, but only in rare circumstances have conditions favoured the formation of significant quantities of the mineral as fibres and fibre bundles. None of that says whether a particular rock, carving or specimen contains chrysotile.
Notifiable, friable, low risk. People also ask whether chrysotile is notifiable, friable or low risk. Those are questions about duties and risk under the regulations, and they belong with HSE’s asbestos pages; HSE’s introduction to asbestos safety says its guidance is for, among others, asbestos surveyors and analysts and licensed contractors. This page gives no answer to them, no verdict on any serpentine or specimen, and no handling, cutting, cleaning or storage advice. A clinician is the route for any health question. This is not health, safety or legal advice.
Where to go next. The jade question is on is serpentine jade, other mineral hazards are routed on toxic minerals in a collection, and more guides are in the collecting guides. Nothing on this site is offered for sale; the wanted list is the only commercial route.