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Silicate

Thomsonite-Sr

NaSr₂(Al₅Si₅)O₂₀·6-7H₂O
Hardness5
Crystal systemOrthorhombic
ClassSilicate
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Thomsonite-Sr

Thomsonite-Sr is an IMA-recognized mineral species in the silicate class, with the chemical formula NaSr₂(Al₅Si₅)O₂₀·6-7H₂O.

It crystallizes in the orthorhombic crystal system (space group Pcnn). It is a member of the Thomsonite structural group.

Key properties: Mohs hardness 5; specific gravity 2.47; White streak; Vitreous luster; optically biaxial.

IMA symbol Thm-Sr, IMA status: approved, named in 2000.

Found in hydrothermal veinlets that cut the natrolite-bearing core of a pegmatite in an alkaline massif.

It is found associated with Microcline, aegirine, annite, astrophyllite, magnetite, fluorapatite, pyrophanite, thomsonite-Ca (Mt. Rasvumchorr); calcite, tobermorite, fluorapophyllite.

The suffix alludes to the predominance of Sr rather than Ca in the thomsonite series.

Index entry. This entry combines official IMA/RRUFF species data with published physical-property data — a full written entry hasn’t been published yet. Browse more T minerals or help write this entry.