Home > Mexico III Ojuela I – January 12 > MS1732 Segnitite with gem Mimetite

Segnitite with gem Mimetite


Segnitite is a hydrogen-bearing (acid) lead iron arsenate, and a member of the alunite supergroup (Bayliss et al., 2010). Birch et al. (1992) named the mineral after Dr. E. Ralph Segnit (1923-1999), mineralogist and petrologist at the University of Adelaide, for his contributions to Australian mineralogy. This specimen comes from a 2010 find of lead arsenates at Ojuela. Segnitite is the oldest mineral in the sequence, forming a matrix for later deep brown tsumcorite (not present on this piece), rare yellow arsenbrackebuschite, and lastly gem mimetite.

Gem mimetite crystals here to 1.0 cm are flat-lying in a shell of drab green segnitite. Some are doubly terminated. The bulk of this specimen consists of microcrystalline segnitite. There are a very few crystals of arsenbrackebuschite present. The identification of segnitite is based on both SEM-EDS and Raman spectroscopy.

Price: $350

Item code: MS1732

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