Is scolecite asbestos
UK law defines asbestos as six named fibrous silicates. Scolecite, a zeolite of hardness 5 to 5.5, is not among them, though its sheet records fibrous masses.
Is scolecite asbestos? Not by name. Regulation 2 of the UK Control of Asbestos Regulations 2012 defines asbestos as six named fibrous silicates; scolecite, a calcium zeolite of hardness 5 to 5.5, is not one. Its Handbook sheet does record fibrous masses. Whether a specimen is a hazard is for HSE and a clinician, not this page.
In short
- UK law defines asbestos by name. Regulation 2 of the Control of Asbestos Regulations 2012 reads: asbestos means the following fibrous silicates: asbestos actinolite, asbestos grunerite (amosite), asbestos anthophyllite, chrysotile, crocidolite and asbestos tremolite, each with a CAS number. Scolecite is not on the list.
- Scolecite is a silicate and can be fibrous, but neither puts it on the list. Its Handbook sheet records slender prismatic crystals to 30 cm, characteristically in radiating sprays, fibrous masses, and places it in the zeolite group. The regulation names minerals; it does not define asbestos as any fibrous silicate.
- Fibrous is common; asbestiform is not. Of the 176 sheets in this site's reference set, 57 record a fibrous habit, 15 of the 55 silicate sheets among them, and 4 of the 9 zeolite-group sheets. One sheet uses the word asbestiform: actinolite, radiating fibrous to asbestiform.
- Not named is not the same as assessed safe. This page reports what the regulation names and what the scolecite sheet records. It does not say scolecite is, or is not, a health hazard. Questions about exposure go to HSE and a clinician, and workplace duties sit in the regulations themselves. This is not health, safety or legal advice.
- The same test answers okenite and crocoite. Neither is named in regulation 2. Crocoite is lead chromate, not a silicate at all; okenite is a calcium silicate whose sheet, outside the 176, records it as typically fibrous.
| Mineral | As written in regulation 2 | CAS number in regulation 2 | Sheet in this site's 176? | Habit the Handbook sheet records | Named in regulation 2? |
|---|---|---|---|---|---|
| Actinolite | asbestos actinolite | 77536-66-4 | Yes | Bladed crystals to 15 cm; radiating fibrous to asbestiform | Yes, as asbestos actinolite |
| Grunerite | asbestos grunerite (amosite) | 12172-73-5 | No | No sheet in the set | Yes, as asbestos grunerite (amosite) |
| Anthophyllite | asbestos anthophyllite | 77536-67-5 | No | No sheet in the set | Yes, as asbestos anthophyllite |
| Chrysotile | chrysotile | 12001-29-5 or 132207-32-0 | No | No sheet in the set | Yes |
| Crocidolite | crocidolite | 12001-28-4 | No | No sheet in the set | Yes |
| Tremolite | asbestos tremolite | 77536-68-6 | Yes | Crystals to 20 cm; also fibrous, granular or columnar aggregates | Yes, as asbestos tremolite |
| Scolecite | Not named | None given | Yes | Slender prismatic crystals to 30 cm; radiating sprays, fibrous masses | No |
| Natrolite | Not named | None given | Yes | Prismatic crystals to 1 m; also radiating fibrous | No |
| Mesolite | Not named | None given | Yes | Prismatic crystals to 20 cm; hairlike tufts and aggregates of fibres | No |
| Okenite | Not named | None given | No; a comparator sheet outside the 176 | Typically fibrous; compact radial fibrous balls to 4 cm | No |
| Crocoite | Not named; a chromate, not a silicate | None given | Yes | Prismatic to acicular crystals to 15 cm; radial sprays | No |
Is scolecite asbestos? What regulation 2 names, quoted
Definition first: in UK law, asbestos is what regulation 2 of the Control of Asbestos Regulations 2012 names, and it names six minerals. The text reads asbestos means the following fibrous silicates, then lists (a) asbestos actinolite, (b) asbestos grunerite (amosite), (c) asbestos anthophyllite, (d) chrysotile, (e) crocidolite and (f) asbestos tremolite, each with its CAS Registry Number, as set out in the table above. Scolecite is not one of the six. The same regulation sets a control limit of 0.1 fibres per cubic centimetre of air averaged over a continuous period of 4 hours. The text was read on legislation.gov.uk on 30 September 2026, in its revised form.
Three of the six carry the word asbestos in front of a mineral name. The regulation writes asbestos actinolite and asbestos tremolite, not actinolite and tremolite. This page does not interpret what that wording covers; it quotes it. The actinolite page quotes the same text.
Scolecite, as the Handbook of Mineralogy records it, is CaAl2Si3O10·3H2O, a member of the zeolite group; the IMA list writes the formula Ca(Si3Al2)O10·3H2O. It is hardness 5 to 5.5, brittle, with perfect cleavage on {110} and {1-10}, indices read from the rendered sheet. The species itself is covered on scolecite.
Scolecite is fibrous on its sheet: why that does not make it asbestos
The scolecite sheet records slender prismatic crystals to 30 cm, characteristically in radiating sprays and fibrous masses. A fibrous habit is a shape. The regulation's list is a list of names, so a fibrous habit alone does not add a mineral to it.
Method. The 176 sheets in this site's reference set were converted with pdftotext -layout, and each Crystal Data field was searched case-insensitively for fibrous, allowing for the fi ligature, which many sheets render as a stray glyph. Scolecite's own sheet is typeset that way and had to match as a positive control, and did; gypsum, typeset plainly, was the second control. 57 sheets record a fibrous habit; a literal search finds only 42. Of the 55 sheets with silicon in the formula, 15 do. Of the 9 sheets whose Mineral Group line names the zeolite group, 4 do: gonnardite, mesolite, natrolite and scolecite.
One sheet of the 176 uses the word asbestiform: actinolite, whose habit reads radiating fibrous to asbestiform. Tremolite's sheet records fibrous aggregates without the word. The word asbestos appears on 9 other sheets only in locality names, such as Asbestos in Quebec, Asbest in the Urals and the Johnston asbestos mine, which the count excludes. None of the four other minerals regulation 2 names has a sheet in the set.
What this page does not decide, and who does
This page does not say whether scolecite, or any fibrous specimen, is a health hazard. A mineral missing from regulation 2 has not thereby been assessed as safe; the regulation is a legal definition for work with asbestos, not a list of every fibrous mineral that has been studied. Nothing here is a finding either way.
Where the answers are. The HSE asbestos pages cover the duties, the law and licensed work. Workplace exposure limits are in HSE EH40, and control of hazardous substances at work falls under the COSHH Regulations 2002. A concern about exposure belongs with a clinician. This site's general page on toxic minerals in a collection covers minerals in a collection. This is not health, safety or legal advice.
No handling advice is given here, deliberately: the scope of this page is what the law names and what the sheet records.
Is okenite or crocoite asbestos? The same name test
The name test: under regulation 2 a mineral is asbestos only if it is one of the six named; a fibrous habit does not add a seventh, and a missing name does not make a mineral safe. Applied to the three minerals that appear beside the word asbestos in search suggestions:
- Scolecite: a calcium zeolite, fibrous masses on its sheet, not named.
- Okenite: not named. Its Handbook sheet, which is outside this site's 176, records bladed crystals or laths, typically fibrous, in compact radial fibrous balls to 4 cm; its formula is Ca5Si9O23·9H2O on the sheet and Ca10Si18O46(H2O)18 on the IMA list.
- Crocoite: not named, and outside the regulation's opening words altogether, because it is lead chromate, PbCrO4, not a silicate. Its sheet records prismatic to acicular crystals to 15 cm in radial sprays.
The zeolites as a group are set out on which minerals are zeolites. The safety and conservation pages are indexed at the collecting guides. Nothing on this site is offered for sale; the wanted list is the only commercial route.