Vibrational spectroscopy of the borate mineral gaudefroyite Ca4Mn3+3-x (BO3)3(CO3)(O,OH)from N’Chwaning II mine, Kalahari, Republic of South Africa

Frost, Ray L. and Scholz, Ricardo and Lopes, Andres and Xi, Yunfei and Žigovečki Gobac, Željka and Carvalho Lana, Cristiano de (2014) Vibrational spectroscopy of the borate mineral gaudefroyite Ca4Mn3+3-x (BO3)3(CO3)(O,OH)from N’Chwaning II mine, Kalahari, Republic of South Africa. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 120. pp. 265-269.

[img] PDF
Restricted to Registered users only
Language: English

Download (829kB)

Abstract

Gaudefroyite Ca4Mn3+3-x (BO3)3(CO3)(O,OH) is an unusual mineral containing both borate and carbonate groups and is found in the oxidation zones of manganese minerals, and it is black in color. Vibrational spectroscopy has been used to explore the molecular structure of gaudefroyite. Gaudefroyite crystals are short dipyramidal or prismatic with prominent pyramidal terminations, to 5 cm. Two very sharp Raman bands at 927 and 1076 cm-1 are assigned to trigonal borate and carbonate respectively. Broad Raman bands at 1194, 1219 and 1281 cm-1 are attributed to BOH in-plane bending modes. Raman bands at 649 and 670 cm-1 are assigned to the bending modes of trigonal and tetrahedral boron. Infrared spectroscopy supports these band assignments. Raman bands in the OH stretching region are of a low intensity. The combination of Raman and infrared spectroscopy enables the assessment of the molecular structure of gaudefroyite to be made.

Item Type: Article
Keywords: Raman spectroscopy, Infrared spectroscopy, Borate,Gaudefroyite, N’Chwaning II mine
Date: 2014
Subjects: NATURAL SCIENCES > Geology > Mineralogy and Petrology
Divisions: Faculty of Science > Department of Geology
Depositing User: Danica Vujičić
Date Deposited: 02 Jul 2015 09:56
Last Modified: 02 Jul 2015 09:56
URI: http://digre.pmf.unizg.hr/id/eprint/3679

Actions (login required)

View Item View Item