Roumaite
Roumaite is an IMA-recognized mineral species in the silicate class, with the chemical formula (Nb,Ti)(Ca,Na, )₃(Ca,REE)₄(Si₂O₇)₂(OH)F₃.
It crystallizes in the monoclinic crystal system (space group Cc).
Key properties: specific gravity 3.33; White streak; Silky luster.
IMA symbol Rma, IMA status: approved, named in 2008.
A late-stage product of hydrothermal activity in cavities in nepheline syenite in association with a peralkaline complex.
It is found associated with Aegirine, albite, analcime, arfvedsonite, catapleiite, a eudialyte-group mineral, microcline, sodalite, sphalerite, steacyite, villiaumite.
The name refers to Rouma Island, a central island in the lagoon of the Los Archipelago, Guinea, where the first specimens were collected.
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 R minerals or help write this entry.