Carobbiite

Carobbiit, chemically potassium fluoride, is a very rarely occurring mineral from the mineral class of halides. It crystallizes in the cubic crystal system with the chemical composition of KF and forms small, cubic, colorless crystals.

Etymology and history

Naturally occurring potassium fluoride was first found at Vesuvius in Italy and described in 1936 by Italian geologists Guido Carobbi. Recognized as mineral however, it was not until 1956, when Hugo Strunz examined the material again and Carobbis discoveries confirmed. He named the mineral after its original discoverer.

Classification

In the classification of minerals according to Strunz Carobbiit is classified in the simple halides. In the 8th edition it made with Villiaumit, Chlorargyrite, Griceit, halite, sylvite and Bromargyrit a group. In the 9th edition it forms with Villiaumit, Griceit, halite and sylvite a subset of the simple halides without crystal water and a ratio of metal to halide of 1:1 or 2:3.

In the classification of minerals according to Dana it forms with Villiaumit, Griceit, halite and sylvite the Halitgruppe, a subgroup of the anhydrous and hydrous halides with the formula AX.

Education and Locations

Carobbit formed in stalactites in lava caves. It is associated with halite, Mercallit and Hieratit. In addition to the type locality at Vesuvius, another locality in the Prefecture on the Japanese island Hokkaidō Iburi is only known.

Crystal structure

Carobbit crystallizes in the cubic crystal system in the space group with the lattice parameters a = 5.40 Å and four formula units per unit cell.