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Wollastonite

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Key Data

Formula: CaSiO₃ or Ca₂SiO₄
CAS: 13983-17-0
Other names: Calcium silicate, calcium orthosilicate, CalSil
Appearance: White powder
Solubility in water: 0.095g/l. Aqueous solution has a pH of 9.9
Melting Point: 1410 - 1540°C
Dustiness:
Respirable crystalline silica: <1% (by weight)

Composition/Impurities

Wollastonite is strictly CaSiO₃, but one of a range of calcium silicate compounds. Data given here is for CaSiO₃, unless stated otherwise.
A fibrous silicate, but it has no bio-persistence unlike asbestos, so is not associated with the same health risks.
Small amounts of iron, magnesium or manganese may replace some of the calcium.

Uses

Used to introduce calcium with a lower LOI than whiting, so a lower risk of pinholing. It also has a lower melting point.

Exposure Routes

Skin and Eye Exposure

May cause redness of the eyes

Skin Absorption

Not absorbed

Inhalation

May cause coughing

Ingestion

Toxicity

Acute

Skin

None

Inhalation

None

Ingestion

May cause indigestion

Repeat Dose

Skin

None

Inhalation

None

Ingestion

None

Genotoxicity

None

Carcinogenicity

Whilst limited evidence shows that it is probably not carcinogenic, there is insufficient evidence to be certain of this.

Reproductive Toxicity

None

Fire Hazard

Not flammable

Health and Safety Practice

Standard dust precutions

Disposal

Regulatory Requirements

Dust Limits

_Regulator_	_8hr TWA mg/m³_	_15min TWA mg/m³_	_Notes_
UK HSE	10		All calcium silicates. Inhalable.
UK HSE	4		All calcium silicates. Respirable.