Could you be more specific? I'm curious.
Edit: Hmm, thinking about Mazek surname… It could be possibly Marzek, which is now transcripted as Marek (Mark). It's a Czech name, although "rz" is a Polish letter = ř in Czech. But assuming your ancestors came from Czech lands and names were written in various forms few centuries ago, we can keep claiming it's a Czech surname in your case.