I wish I had an answer. But I don't - I just hated seeing no replies to your question. I was hoping someone would answer, because I'm going to be buying some mica soon and I would like to know, too!
i put my mica in a small glass dish and add about 1 tsp of water and stir. i then heat it in the microwave for 15 secs and stir again. i then add it to my melted soap. this way the heat will help dissolve it and you can smash any clumps before adding it to the soap.