Rhyolite Glass Standards

[dhburns]

After private discussions with a few folks on this forum, it seems there are some major issues with some of our well known natural rhyolite glass standards (e.g., VG568, RLS, Astimex, etc.). These issues range from incorrect published values to considerable heterogeneity within and/or between shards/grains (in this case, we are just interested in major and minor element concentrations).

Which natural rhyolite glass standards are folks out there using, and what are some of the issues you are running into? Alternatively, has anyone found the one standard to rule them all? 

[Probeman]

I think it's a mistake for us to rely on natural standard materials for all the reasons Dale described, not to mention limited supply. Here's a discussion on using synthetic materials for trace element standards, but it applies to major element standards as well:

https://probesoftware.com/smf/index.php?topic=928.0

I have some old rhyolite glasses from Carmichael but they are also slightly inhomogeneous. So I prefer to utilize the NIST mineral glasses for all major element characterization in glasses and just run the USGS synthetic BIR-1G (basaltic glass) as a secondary standard. All three agree very well with each other.

But I'd be interested in what others have found.  But I'd also encourage the production of a sufficient quantity of a synthetic Si rich glass as a community standard...