certainty of origin : Cotype (used for additional information).
author(s) : Marmo
date of publication : 1959
source : Schweiz.Min.Petr.Mitt.(39) p.125
formula : Al2O3 4-5SiO2 3-4H2O
comments about the origin : "echantillon NoVM4991A" original de Marmo, 1977
This type specimen, kept in the Museum of Ecole des mines de Paris, has been indexed by Dr Guillemin.
(C) BRGM, ENSMP