Iron transformers esp power ones have iron laminates, dozens of thin metal plates bolted or welded togther.
If the core has a dark smooth finish then its probably iron powder or ferrite, iron powder cores are common for medium freq applications, filter chokes in pc power supplies are often iron powder, they often have a coloured stripe on to denote the material.
There are different types of ferrite too, but unless marked you need special gear to measure the parameters, 80's on tv flyback's are usually ferrite.
To build a cfl driver I'd salvage a ferrite power trans, heat it up with an air gun, take it apart and rewind it, try googling for cfl joule thief driver.