Clay will not melt or even dissolve in your MP soap. It is going to stay as little flecks like that. If you pour cooler (just before the soap sets up) you can suspend the clay in the soap so it doesn't fall into all of the little details of your soap.
Its probably best to use clays in an opaque MP soap.
ETA: It still looks very pretty to me. The clay almost looks like highlights for the details in the soap.
I have read that when using clay as a colorant, you need to break it down in liquid first or it will clump in your soap. Disperse the clay in a small amount of rubbing alcohol first to make a liquid, then add that to your soap. I have not tried clay personally, so you may want to do further reading.