The Raman spectrum of omphacite (see above spectrum) reveals the characteristic bands of clinopyroxenes. The stretching modes of Si-O_nbr appear as five bands, with 1013 cm^-1 at the highest intensity, and the Si-O_br modes as one band at 667 cm^-1. The bending modes of Si-O bonds are observed in the 450-570 cm^-1 region as four bands. As in the other cases, below 400 cm^-1 are located the modes of the interactions between cation and oxygen (see below table).

The Raman spectrum reported by Downs (2006) is not comparable with that obtained in the present study (see below table). The measured chemistry of sample R061129 (Downs, 2006) is given by the formula (Ca_0.51Na_0.49)(Mg_0.43Al_0.42Fe²⁺_0.08Fe³⁺_0.07)[Si₂O₆]. Our Raman spectrum of omphacite is more similar to the diopside spectrum, which leads to the conclusion that our sample is characterized by a higher concentration of Ca and Mg.

• The Mineralogy Database [link]

• Crystal data (.cif file) from the American Mineralogist Crystal Structure Database [link]

• ¹BUZATU A., BUZGAR N. (2010) - The Raman study of single-chain silicates. Anal. Şt. Univ. “Al. I. Cuza” Iaşi, Geologie, LVI/1. [link]

• Downs, R.T., (2006) - The RRUFF Project: an integrated study of the chemistry, crystallography, Raman and infrared spectroscopy of minerals. Program and Abstracts of the 19th General Meeting of the International Mineralogical Association in Kobe, Japan. (www.rruff.info).