Strontianite

Strontianite
Strontianite
	Strontianite from Slovakia
General
Category	Carbonate minerals
Formula; (repeating unit)	SrCO3
IMA symbol	Str
Strunz classification	5.AB.15 (10 ed) ; 5/B.04-20 (8 ed)
Dana classification	14.01.03.03
Crystal system	Orthorhombic
Crystal class	Dipyramidal (mmm) ; H-M symbol: (2/m 2/m 2/m)
Space group	Pmcn
Unit cell	a = 5.1 Å, b = 8.4 Å ; c = 6.0 Å; Z = 4
Identification
Formula mass	147.63 g/mol
Color	Colourless, white, gray, light yellow, green or brown; colourless in transmitted light
Crystal habit	Prismatic, acicular, pseudo hexagonal, columnar to fibrous, granular, massive
Twinning	Very common, usually contact, rarely penetration, also repeated
Cleavage	{110} nearly perfect, {021} poor, {010} traces
Fracture	Subconchoidal to uneven
Tenacity	Brittle
Mohs scale hardness	3+1⁄2
Lustre	Vitreous, resinous on breaks, greasy
Streak	White
Diaphaneity	Transparent to translucent
Specific gravity	3.74 to 3.78 Transparent versions are heavier than the other ones
Optical properties	Biaxial (−)
Refractive index	nα = 1.52, nβ = 1.66, nγ = 1.67
Birefringence	0.15
2V angle	Measured: 7°, Calculated: 12° to 8°
Ultraviolet fluorescence	Almost always fluorescent
Solubility	Soluble in dilute HCl
Alters to	Celestine SrSO4
References

Strontianite (Sr C O₃) is an important raw material for the extraction of strontium. It is a rare carbonate mineral and one of only a few strontium minerals. It is a member of the aragonite group.

Aragonite group members:^[2] aragonite (CaCO₃), witherite (BaCO₃), strontianite (SrCO₃), cerussite (PbCO₃)

The ideal formula of strontianite is SrCO₃, with molar mass 147.63 g,^[4] but calcium (Ca) can substitute for up to 27% of the strontium (Sr) cations, and barium (Ba) up to 3.3%.^[2]

The mineral was named in 1791 for the locality, Strontian, Argyllshire, Scotland, where the element strontium had been discovered the previous year.^[2] Although good mineral specimens of strontianite are rare, strontium is a fairly common element, with abundance in the Earth's crust of 370 parts per million by weight, 87 parts per million by moles, much more common than copper with only 60 parts per million by weight, 19 by moles.^[6] Strontium is never found free in nature. The principal strontium ores are celestine SrSO₄ and strontianite SrCO₃. The main commercial process for strontium metal production is reduction of strontium oxide with aluminium.^[6]

^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
^ ^a ^b ^c ^d Gaines et al (1997) Dana’s New Mineralogy Eighth Edition. Wiley
^ Strontianite on Mindat.org retrieved 23/08/11
^ ^a ^b Barthelmy, Dave. "Strontianite Mineral Data". Retrieved 23 August 2011.
^ "Strontianite in the Handbook of Mineralogy" (PDF). Retrieved 24 August 2011.
^ ^a ^b "Strontium". Retrieved 24 August 2011.

[1] Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.

[Dana-2] Gaines et al (1997) Dana’s New Mineralogy Eighth Edition. Wiley

[Mindat-3] Strontianite on Mindat.org retrieved 23/08/11

[Webmin-4] Barthelmy, Dave. "Strontianite Mineral Data". Retrieved 23 August 2011.

[HOM-5] "Strontianite in the Handbook of Mineralogy" (PDF). Retrieved 24 August 2011.

[Chemicool-6] "Strontium". Retrieved 24 August 2011.

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