Very small but sharp crystal of the extremely rare mineral tweddillite from the type locality in Wessels mine (North Cape Province, South Africa). Tweddillite is one of the rarest minerals from Wessels mine and it is very rarely seen in the systematic mineral market. — Photo: David Hospital · CC BY-SA 4.0
Tweddillite
Tweddillite is an IMA-recognized mineral species in the silicate class, with the chemical formula CaSr(Mn³⁺₂Al)[Si₂O₇][SiO₄]O(OH).
It crystallizes in the monoclinic crystal system (space group P2_1/m). It is a member of the Clinozoisite, Epidote structural group.
IMA symbol Twe, IMA status: approved, named in 2001.
Index entry. This entry combines official IMA/RRUFF species data with published physical-property data — a full written entry hasn’t been published yet.
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