mineral+water+standard

Hi-

I am trying to develop analytical capability to analyze dD, d18O in minerals associated with hydrothermal systems. I've set up a combustion furnace inline with an LGR laser analyser, similar to the following. At this point, I've only run water standards through, and am looking to move to a mineral standard. I just wanted to get in contact to see if anyone had advice in regards to developing a solid standard for analysis of H and O. Gypsum seems like a potentially good option. Any tips on suppliers, or minerals to target would be helpful!

Thanks, John (University of Waikato NZ)