Cast iron cookware can be magnetized and should work fine on an induction cooktop. If you tend to slide the pan around on the surface a lot, are are worried about scratching of the glass, you can use a piece of parchment paper (aka bakery paper) available at any grocery store. Just place the paper on the surface. Since there is no open flame or exposed heating element, it won't burn, just like in the oven. Some people even use plain old paper towel, but I'm not sure I'm comfortable with that suggestion.