@article{articlec3b58635,
title   = {Stoichiometry-based estimates of ferric iron in calcic, sodic-calcic and sodic amphiboles: a comparison of various methods},
author = {Gualda, Guilherme Augusto Rosa and Vlach, Silvio Roberto Farias},
year = {2005},
doi = {10.1590/s0001-37652005000300012},
journal   = {Anais da Academia Brasileira de Ciências}
}