rockm

Mica pots are made with mica--http://minerals.usgs.gov/minerals/pubs/commodity/mica/

and plastic. Mica bonsai pots are fine for training or even for display, if you like them.

However, actual, honest-to-God clay bonsai pots are much much much more versatile and infinitely more attractive than mica pots. There are perhaps two dozen (probably less) mica pot designs--and only one color. "Real" bonsai pots come in thousands of designs and as many colors/glazes and textures. If you have a tree that is particularly nice, it deserves a nice pot...

Good clay pots can be found for as much--or even less--than what a mica one costs.

Plastic-only pots are simply crap. They will wrack when you pick them up. They're flimsy and can wreck roots when they bend suddenly. They can shatter in cold weather. They also break down if left exposed to sunlight for a couple of years. Don't use them.