SEM image of the crystals of verneite in association with fine-grained jakobssonite in the cotype sample from Eldfell." Image and caption taken from Balić-Žunić, T., Garavelli, A., Pinto, D. and Mitolo, D. (2018) Verneite, Na2Ca3Al2F14, a new aluminum fluoride mineral from Icelandic and Vesuvius fumaroles. Minerals: 8: 553-562. https://www.mdpi.com/2075-163X/8/12/553/pdf The article is open access, Creative Commons Attribution. From: Eldfell, Heimaey island, Vestmannaeyjar archipelago, Vestmannaeyjar, Southern Region, Iceland — Photo: Balić-Žunić, T., Garavelli, A., Pinto, D. and Mitolo, D. · CC BY 3.0
Jakobssonite
Jakobssonite is an IMA-recognized mineral species in the halide class, with the chemical formula CaAlF₅.
It crystallizes in the monoclinic crystal system (space group C2/c).
Key properties: specific gravity 2.89; Earthy luster.
IMA symbol Jak, IMA status: approved, named in 2011.
Forms crusts around fumaroles in active basaltic volcanoes.
It is found associated with Ralstonite, gypsum, hematite, anhydrite, opal-A (Eldfell volcano); leonardsenite, heklaite, malladrite, hieratite, fluorite, chiolite.
The mineral was named to honor Sveinn Peter Jakobsson (b. 1939), one of Iceland’s leading volcanologists, and because he was the first person to recognize the mineral.