The paramagnetic resonance spectrum of light-green natural enstatite,
(Mg, Fe(2+)) [SiO(3)] shows evidence of Fe(3+) in triclinic site
symmetry. Only one transition of sufficient intensity could be evaluated
with the following Hamiltonian parameters: g(xx)=4.774, g(yy)=4.003,
g(zz)=3.723. No hyperfine splitting was detected. It is suggested that
Fe(3+) should occupy the more distorted M(2) site. A number of spread
signals of very low intensity from 50 to 500 mT can be attributed to
other Fe(3+) transitions or to Mn(2+). The occurrence of a small portion
of iron in a trivalent state could be due to either oxidizing conditions
during crystal growth or to subsequent ionizing radiation
