Ussingite

Ussingite is a very common mineral in the Lovozero massif, but  almost absent in the Khibiny massif. Almost every mountain in
Lovozero has Ussingite veins. Ussingite is probably formed by alteration of Analcime veins. Ussingite veins them self will alter to
Natrolite. Allthough most Ussingite on the market is massive, small Ussingite crystals are not uncommon in cavities, such as this one from
Punkaruaiv, southern Lovozero massif.
[photo: Maurice de Graaf, collection Diederik Visser]

This is the more likely way to encounter Ussingite. This hand size specimen is from the Shkatulka vein, Mount Alluaiv.
[photo/collection: Maurice de Graaf]