can cast iron be used on glasstop stoves?
I presume you're referring to "glasstop stoves" and not "cast iron cookware"? /img/vbsmilies/smilies/thumb.gifIt shouldn't be. You'll very likely scratch it up leading to cosmetic and possible heat stress failures. Just another strike against them in my book. They're generally poor performers with slow heating and cooling.
LeCreuset, Staub, etc now put enamel on the bottoms of their cast iron pieces, I think for exactly this reason. They can slide across ceramic top stoves without scratching it.
PHatch, I just bought an Electrolux induction range. I would never go back to a conventional electric or gas top. Besides heating more quickly, its ceramic top is much easier to clean. (Having trouble with the oven thermostat though...since I bake a lot, it's been a real issue and E'lux is trying to fix it.)
I have a ceramic top and use cast iron a lot. I don't have any scratches but I am careful not to drag it across the stove top.
I have a skillet, grill pan and a porcelain lined dutch oven. The grill pan is used several times a week.