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Porous, S‐bearing silica in metal‐sulfide nodules and in the interchondrule clastic matrix in two EH 3 chondrites
Author(s) -
Lehner S. W.,
Németh P.,
Petaev M. I.,
Buseck P. R.
Publication year - 2017
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/maps.12940
Subject(s) - chondrule , pyrrhotite , chondrite , sulfide , mineralogy , geology , porosity , amorphous solid , chemical engineering , chemistry , pyrite , meteorite , crystallography , organic chemistry , physics , geotechnical engineering , astronomy , engineering
Two new occurrences of porous, S‐bearing, amorphous silica are described within metal‐sulfide nodules ( MSN ) and as interchondrule patches in EH 3 chondrites SAH 97072 and ALH 84170. This porous amorphous material, which was first reported from sulfide‐bearing chondrules, consists of sinewy SiO 2 ‐rich areas containing S with minor Na or Ca as well as Fe, Mg, and Al. Some pores contain minerals including pyrite, pyrrhotite, and anhydrite. Most pores appear vacant or contain unidentified material that is unstable under analytical conditions. Niningerite, olivine, enstatite, albite, and kumdykolite occur enclosed within porous silica patches. Porous silica is commonly interfingered with cristobalite suggesting its amorphous structure resulted from high‐temperature quenching. We interpret the S‐bearing porous silica to be a product of silicate sulfidation, and the Na, Ca, Fe, Mg, and Al detectable within this material are chemical residues of sulfidized silicates and metal. The occurrence of porous silica in the cores of MSN , which are considered to be pre‐accretionary objects, suggests the sulfidizing conditions occurred prior to final parent‐body solidification. Ubiquitous S‐bearing porous silica among sulfide‐bearing chondrules, MSN , and in the interchondrule clastic matrix, suggests that similar sulfidizing conditions affected all the constituents of these EH 3 chondrites.