Very dark green crystals of the rare phosphate mineral olgite from the type locality in Kola (Karnasurt Mountain, Lovozero Massif, Murmansk Oblast, Russian Federation). Ex.Dr.Hartel collection. — Photo: David Hospital · CC BY-SA 4.0
Olgite
A rare blue-green sodium-barium-strontium phosphate — demoted in 2008 to a series name for bario-olgite and strontio-olgite.
Intro adapted from Wikipedia (CC BY-SA).
Olgite is an IMA-recognized mineral species in the phosphate class, with the chemical formula (Ba,Sr)(Na,Sr,REE)₂Na(PO₄)₂.
It crystallizes in the hexagonal crystal system (space group P-3m1). It is a member of the Aphthitalite structural group.
Key properties: Mohs hardness 4.5; specific gravity 3.94; Vitreous luster; optically uniaxial.
IMA symbol Olg, IMA status: approved, named in 1979.
Found in nepheline syenite pegmatite in a differentiated alkalic massif.
It is found associated with Natrosilite, analcime.
The mineral was named to honor Ol’ga Anisimovna Vorob’eva (1902–1974), Institute of Mineralogy and Geochemistry of Rare Elements, Moscow, Russia.