Inosilicate (chain silicate), paramorph of eudidymite
Specific gravity: 2.548
Solubility: Insoluble in common acids, soluble in HF (Dana)
Common impurities: Al,Fe,Mg,Ca,K
Plutonic igneous environments
Epididymite occurs in nepheline syenite rocks and their pegmatites as
a late hydrothermal mineral. It may form from pre-existing beryllium minerals and may alter
to bertrandite and beryllite (Dana, HOM).
Associated minerals include albite, aegirine,
leucophanite, natrolite and
At the type locality, the Narssârssuk pegmatite, Narsaarsuk Plateau, Igaliku, Kujalleq, Greenland, Denmark, epididymite occurs as pseudomorphs after chkalovite (Dana).
At Alluaiv Mountain, Lovozersky District, Murmansk Oblast, Russia, At Mt Alluaiv epididymite occurs as pseudomorphs after chkalovite (Dana).
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