Strontium sulfate

Strontium sulfate
Names
	IUPAC name Strontium sulfate
	Other names Celestine
Identifiers
CAS Number	7759-02-6 ;
3D model (JSmol)	Interactive image;
ChemSpider	2341151 ;
ECHA InfoCard	100.028.955
EC Number	231-850-2;
PubChem CID	3084026;
UNII	7Q3KX2L47F ;
CompTox Dashboard (EPA)	DTXSID10884419 ;
	InChI InChI=1S/H2O4S.Sr/c1-5(2,3)4;/h(H2,1,2,3,4);/q;+2/p-2 Key: UBXAKNTVXQMEAG-UHFFFAOYSA-L ; InChI=1/H2O4S.Sr/c1-5(2,3)4;/h(H2,1,2,3,4);/q;+2/p-2 Key: UBXAKNTVXQMEAG-NUQVWONBAV;
	SMILES [Sr+2].[O-]S([O-])(=O)=O;
Properties
Chemical formula	SrSO4
Molar mass	183.68 g·mol−1
Appearance	white orthorhombic crystals
Density	3.96 g/cm3
Melting point	1,606 °C (2,923 °F; 1,879 K)
Solubility in water	0.00138 g/100 mL
Solubility product (Ksp)	3.44×10−7
Solubility	slightly soluble in acids
Band gap	5.92 eV
Magnetic susceptibility (χ)	−57.9×10−6 cm3/mol
Refractive index (nD)	1.622
Structure
Crystal structure	Orthorhombic
Space group	Pnma, No. 62
Point group	mmm
Lattice constant	a = 5.34 Å, b = 6.87 Å, c = 8.36 Å α = 90°, β = 90°, γ = 90°
Lattice volume (V)	306.72 Å3
Formula units (Z)	4
Thermochemistry
Std molar; entropy (S⦵298)	117.0 J⋅mol−1·K-1
Std enthalpy of; formation (ΔfH⦵298)	−1453.1 kJ⋅mol−1
Gibbs free energy (ΔfG⦵)	−1340.9 kJ⋅mol−1
Enthalpy of fusion (ΔfH⦵fus)	36 kJ⋅mol−1
Hazards
	GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H302, H315, H319, H335
Precautionary statements	P261, P305+P351+P338
NFPA 704 (fire diamond)	0 0 0
Related compounds
Other anions	Strontium chloride; Strontium oxide; Strontium sulfite;
Other cations	Beryllium sulfate; Magnesium sulfate; Calcium sulfate; Barium sulfate;
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Strontium sulfate (SrSO₄) is the sulfate salt of strontium. It is a white crystalline powder and occurs in nature as the mineral celestine. It is very poorly soluble in water.

Structure

Strontium sulfate is a polymeric material, isostructural with barium sulfate.^{[citation needed]}

Applications and chemistry

Strontium sulfate is of interest as a naturally occurring precursor to other strontium compounds, which are more useful. In industry it is converted to strontium carbonate (SrCO₃) for use as ceramic precursor and strontium nitrate (Sr(NO₃)₂) for use in pyrotechnics.^[7]

The low aqueous solubility of strontium sulfate can lead to scale formation in processes where these ions meet. For example, it can form on surfaces of equipment in underground oil wells depending on the groundwater conditions.^[8]^[9]

Pyrotechnics

Strontium sulfate is used as a high temperature / flash phase oxidizer in some red strobing compositions, along with ammonium perchlorate (NH₄ClO₄ and treated magnesium or magnalium powder. One theory as to why this occurs is that the ammonium perchlorate sustains combustion at a very low temperature until enough heat has built up for the sulfate combustion reaction to occur. This reaction is extremely rapid and consumes the portion of the composition that was hot enough for the sulfate to act as an oxidizer producing a rapid flash of light, the ammonium perchlorate-metal portion of the composition continues burning with very little flame, and the cycle repeats.^[10]

Biological role

Crystallized strontium sulfate is utilized by a small group of radiolarian protozoa, called the Acantharea, as a main constituent of their skeleton.^{[citation needed]}

References

^ Shimizu, Takeo (February 1994). Stabilizing Firework Compositions | I. Minimum Solubility Law to Foresee the Degeneration | II. A New Chemical Method of Magnesium Coating (PDF). 19th International Pyrotechnics Seminar. Proceedings of the 19^th International Pyrotechnics Seminar. Christchurch: South Pacific Information Services. pp. 1–18.
^ ^a ^b "Materials explorer - SrSO4". next-gen.materialsproject.org. The Materials Project. Retrieved 3 May 2026.
^ Patnaik, Pradyot (2003). Handbook of Inorganic Chemical Compounds. McGraw-Hill. pp. 560–576. ISBN 0-07-049439-8. Retrieved 2009-06-06.
^ ^a ^b Haynes, William M., ed. (2016). CRC Handbook of Chemistry and Physics (97th ed.). Boca Raton, Florida: CRC Press. pp. 4–88, 4–130, 5–36, 5–178, 6–161. ISBN 9781498754293.
^ Sigma-Aldrich Co., Strontium sulphate.
^ "Strontium sulfate SDS" (pdf). www.fishersci.com. ThermoFisher Scientific. 24 December 2025. p. 2. Retrieved 3 May 2026.
^ MacMillan, J. Paul; Park, Jai Won; Gerstenberg, Rolf; Wagner, Heinz; Köhler, Karl; Wallbrecht, Peter (2002). "Strontium and Strontium Compounds". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a25_321. ISBN 978-3-527-30673-2.
^ Jacques, Donald F.; Bourland, Brent I. (1983). "A Study of Solubility of Strontium Sulfate". Society of Petroleum Engineers Journal. 23 (2): 292–300. doi:10.2118/9625-PA.
^ Dean, S. W.; Ezuber, Hosni M. (2007). "Prediction of Strontium Sulfate Scale Formation in Oilfield Environment". Journal of ASTM International. 4 (6) 100958. doi:10.1520/JAI100958.
^ Shimizu, Takeo (1991). "15.2 - Table 22 - Twinklers of the ammonium perchlorate base". Fireworks: The Art, Science, and Technique (3rd ed.). Austin, Tex., U.S.A: Pyrotechnica Publications. p. 224. ISBN 0-929388-05-4.

[1] Shimizu, Takeo (February 1994). Stabilizing Firework Compositions | I. Minimum Solubility Law to Foresee the Degeneration | II. A New Chemical Method of Magnesium Coating (PDF). 19th International Pyrotechnics Seminar. Proceedings of the 19^th International Pyrotechnics Seminar. Christchurch: South Pacific Information Services. pp. 1–18.

[MatExplorer-2] "Materials explorer - SrSO4". next-gen.materialsproject.org. The Materials Project. Retrieved 3 May 2026.

[3] Patnaik, Pradyot (2003). Handbook of Inorganic Chemical Compounds. McGraw-Hill. pp. 560–576. ISBN 0-07-049439-8. Retrieved 2009-06-06.

[CRC-4] Haynes, William M., ed. (2016). CRC Handbook of Chemistry and Physics (97th ed.). Boca Raton, Florida: CRC Press. pp. 4–88, 4–130, 5–36, 5–178, 6–161. ISBN 9781498754293.

[Sigma-5] Sigma-Aldrich Co., Strontium sulphate.

[FisherSDS-6] "Strontium sulfate SDS" (pdf). www.fishersci.com. ThermoFisher Scientific. 24 December 2025. p. 2. Retrieved 3 May 2026.

[7] MacMillan, J. Paul; Park, Jai Won; Gerstenberg, Rolf; Wagner, Heinz; Köhler, Karl; Wallbrecht, Peter (2002). "Strontium and Strontium Compounds". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a25_321. ISBN 978-3-527-30673-2.

[8] Jacques, Donald F.; Bourland, Brent I. (1983). "A Study of Solubility of Strontium Sulfate". Society of Petroleum Engineers Journal. 23 (2): 292–300. doi:10.2118/9625-PA.

[9] Dean, S. W.; Ezuber, Hosni M. (2007). "Prediction of Strontium Sulfate Scale Formation in Oilfield Environment". Journal of ASTM International. 4 (6) 100958. doi:10.1520/JAI100958.

[Shimizu-10] Shimizu, Takeo (1991). "15.2 - Table 22 - Twinklers of the ammonium perchlorate base". Fireworks: The Art, Science, and Technique (3rd ed.). Austin, Tex., U.S.A: Pyrotechnica Publications. p. 224. ISBN 0-929388-05-4.

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