Currently I am working on the clay mineral analysis for an IODP core. I am using a standard clay mineral separation technique by adding H2O2 and acetic acid for the removal of organic and carbonate fraction in ultrasonic bath, after that centrifuging the sample in de-ionized water at 4600 rpm for 6 minutes, and then separate the clay fraction on glass mounts. But the result i am getting is not satisfactory. Sometimes cracks appear in the clay paste on the mount and sometimes i am getting a very minute grainy fraction as well on in the clay paste which become visible when the clay drys on the mount. Is there any step I am missing?

P.S: I have to run these samples on XRD.

It would be very helpful if someone can please explain the process step by step.

Thanks