Scapolite is the name of a series between the sodium chloride rich mineral called marialite and the calcium carbonate rich mineral meionite. Scapolite forms in — Photo: Shannon Heinle · CC0
Meionite
The calcium end-member of the scapolite series, first found in 1801 on Vesuvius's Monte Somma.
Intro adapted from Wikipedia (CC BY-SA).
Meionite is an IMA-recognized mineral species in the silicate class, with the chemical formula Ca₄Al₆Si₆O₂₄(CO₃).
It crystallizes in the tetragonal crystal system (space group P4_2/n). It is a member of the Scapolite structural group.
Key properties: Mohs hardness 5.5–6; specific gravity 2.74–2.78; typically colorless or white or gray or yellow; White streak; Vitreous to pearly or resinous luster; optically uniaxial.
IMA symbol Me, grandfathered status — known before the IMA’s founding, named in 1801.
is typically found in regionally metamorphosed rocks, especially marbles, calcareous gneisses, granulites, and greenschists. Also in skarns, some pegmatites, pneumatolytically or hydrothermally altered mafic igneous rocks.
It is found associated with Plagioclase, garnet, pyroxenes, amphiboles, apatite, titanite, zircon.
Its name comes from the Greek for less, referring to its less acute pyramidal form compared with vesuvianite.
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