Optical absorption and EPR studies on beaverite mineral

The behaviour of transition metal ions in beaverite mineral has been studied by spectroscopic techniques such as electron paramagnetic resonance and absorption spectroscopy in the UV–vis and NIR regions. The ground state of Cu(II) ion in beaverite is confirmed as 2B1g since g∥ > g⊥ (2.42 > 2.097). A resonance noticed at g = 2.017 is ascribed to Fe(III) impurity. Two sets of three characteristic bands observed in the optical absorption spectra are assigned to the same transitions, 2B1g → 2A1g, 2B1g → 2B2 and 2B1g → 2Eg of Cu(II) ion in tetragonal field. The presence of Fe(III) bands is supportive evidence for iron impurity in the mineral. Mid infrared spectrum is due to overtones and combination tones of water and hydroxyl groups.