I have some selected samples with basaltic in composition and vesicular texture. All of the primary constituents are fresh, and they don't have any alteration in thin sections. However, their vesicles typically filled by zeolite, carbonate, and other secondary minerals. I want to do a geochemical analysis for them. So I want to know, there are any effective methods to eliminate these secondary minerals, especially zeolites?
Looking forward to your valuable replies. Much appreciated!
If there is no other option to determine the chemical composition than using EMPA and SEM/EDX-WDX and given the amygdules are filled with light minerals such as zeolites, carbonates and Fe-poor chlorites or smectites a heavy liquid separatation is possible at a grain size > 63µm with Na polytungstate which can be adjusted to different levels of specific gravity. You will only get density groups but no pure mineral suites.
Kind regards
H.G.Dill
If you want clean mineral separates at the coarsest grain size then a Selfrag EPD system may be a good method for you. It uses high voltage electrical pulses to disaggregate samples along grain boundaries. This is particularly useful when glass around grains would contaminate separates, and also make them all look similar. This means hand picking is a lot more fun!
Dear Meysan Akbari,
I would dig out the amygdules manually under a good binocular. So you are in control what crystallized in the center or the rim. Then do XRD on the material. Simultaneously, prepare a thin section of the rock with amygdules which you can look at under the microscope, SEM or use for microprobe analysis to determine the chemical composition. Good luck!
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