Re: [meteorite-list] Quartz on meteorites

2017-09-25 Thread ALAN RUBIN via Meteorite-list
Meteorite-list > Enviada em: sábado, 23 de setembro de 2017 21:28 > Para: Abdelfattah Gharrad > Cc: Meteoritecentral List > Assunto: Re: [meteorite-list] Quartz on meteorites > > > > A few meteorites do contain rare grains of SiO2 including tridymite, > quartz and cris

Re: [meteorite-list] Quartz on meteorites

2017-09-25 Thread Carl Esparza via Meteorite-list
Hello, I think the question came up because of a facebook post in Meteorites by Stefan Ralew that says; "Probably the oldest quartz crystals of the solar system (quartz or tridimite). Found in a ungrouped achondrite meteorite from the Sahara. More information will follow...". Along with a really

Re: [meteorite-list] Quartz on meteorites

2017-09-25 Thread Carl Agee via Meteorite-list
Hi Alan, Perhaps you missed our talks at MetSoc: https://www.hou.usra.edu/meetings/metsoc2017/pdf/6129.pdf https://www.hou.usra.edu/meetings/metsoc2017/pdf/6268.pdf NWA 9 has more than 20% silica polymorphs (mix of tridymite and cristobalite). Best regards, Carl **

Re: [meteorite-list] Quartz on meteorites

2017-09-25 Thread ALAN RUBIN via Meteorite-list
A few meteorites do contain rare grains of SiO2 including tridymite, quartz and cristobalite, but generally these grains are quite small and intergrown with other silicate phases. Some IVA irons contain a few blades of trydimite, but if you see a rock with several percent or more of quartz grains t

[meteorite-list] Quartz on meteorites

2017-09-23 Thread Abdelfattah Gharrad via Meteorite-list
Hello members, I really want to post my question about quartz longtimes ago, what I learned that if one sees quartz on a stone then the stone is not meteorite. in my knowledge there are different types of quartz and whose chemical formula is SiO2. habitually no quartz in the meteorites but