Michail N. Taran

TL;DR: In this paper, a tourmaline solid solution containing Fe, Fe+ Ti, Cr, Ni, Cu, Co, and Mn chromophoric centers has been grown hydrothermally at 650°C and 1,5 kbar on natural seeding plates close to the elbaite composition.

TL;DR: In this article, the authors analyzed and studied natural Fe2+, Fe3+-bearing spinel solid solutions from the spinel s.s.-hercynite and gahnite-hercynsite series in the spectral range 30000-3500 cm−1 in the temperature and pressure ranges 77 ≤ TK ≤ 600 and 10−4 ≤ PGPa ≤ 11.0.

TL;DR: In this paper, the authors studied the optical absorption spectra of natural Co-bearing spinel and staurolite at different temperatures and pressures and found that the splitting of the spin-allowed bands I and II of IV Co 2+ is caused by spin-orbit and vibronic coupling.

TL;DR: In this paper, the authors studied single crystals of several varieties of dumortierite, an orthorhombic, pseudohexagonal borosilicate mineral with spectacular colour and pleochroism, and found that the excitation occurs between Fe 2+ and Ti 4+ substituting for Al in the face-sharing M(1) octahedra forming straight chains II, in which the metal positions are partly vacant and the metal ions next to such voids are off-centred.

TL;DR: A broad (FWHM ≈ 7300 cm−1) intense band at ~21 700 cm− 1 in the optical absorption spectra of natural Fe2+, Fe3+-rich garnets is attributed to electronic intervalence charge-transfer transitions (IVCT), VIIIFe2+ + VIFe3+ → VIIIF e3++ VIF e2+. In Fe3+, Fe2+-bearing garnets of predominantly almandine compositions, this band causes yellowish tinges in addition to the pink color, typical of pure Fe 3+-