Home > Mexico III Ojuela I – January 12 > MS1738 Tsumcorite on Segnitite

Tsumcorite on Segnitite


Tsumcorite is a hydrated lead zinc arsenate, originally found at Tsumeb, Namibia. Geier et al. (1971) named the mineral after the Tsumeb Corporation Ltd., recognizing their support of mineralogical sciences. 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, rare arsenbrackebuschite (not present on this specimen), and lastly mimetite.

Tsumcorite crystals are bladed avergaing 0.5 mm, and interwoven over powdery drab green segnitite. Scattered mimetite crystals to 0.4 cm are also present. The identification of tsumcorite is based upon unit cell determination by single crystal X-ray diffraction combined with semi-quantitative SEM-EDS analysis. The identification of segnitite is based on both SEM-EDS and Raman spectroscopy.

Price: $300

Item code: MS1738

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