Fe2+ - Mg ORDER-DISORDER STUDY IN ORTHOPYROXENES FROM SÃO JOÃO NEPOMUCENO (IVA) IRON METEORITE

DOS SANTOS E.; SCORZELLI R; VARELA M.E.; MUNAYCO P.

Medellin

Conferencia; LACAME; 2012

São João Nepomuceno (SJN) is an iron meteorite belonging to IVA chemical group. It consists of Fe-Ni metal matrix and silicate inclusions made of coarse-grained mixture of tridymite, orthopyroxene and clinopyroxene. Although the extensive work performed on IVA group there is still no consensus about their origin.. The large spread of metallographic cooling rate data argues against a model of origin in a common asteroidal core. Nevertheless it has been shown that chemical characteristics of IVA metal phases are consistent with the core origin in a parent body [1]. Nonetheless, metal ? silicate mixing of the IVA group remains a complex issue.