How to tell if a bracket is made out of cast iron or steel?

I am trying to figure out if my stock bracket that holds the a/c comp and p. steering pump is cast iron or cast steel. Is there an easy way to figure it out? Does a magnet stick to cast iron?

i think magnets stick to cast iron, what year truck/motor we lookin at?

It is on a 2000 c3500 7.4 litre. I had to cut it down to fit my a/c compressor under my hood with the body drop. I was planning on welding to it but I was able to make some brackets bolt on to it. It looks like steel but it cut very easy with a sawzall and its like 1/4" thick so it must be cast. thanks for your help

also can go by looks of the surface

typically manufacturers will not take the time to have a smooth machine finish on cast parts, that's why they cast them to begin with to save time on machining, which also depends on the casting procedure used.

if it is a steel part it will be finished since it had to have been machined to take its shape. so cast parts typically will have a rough surface finish, most of the time, but not always.

CAST ALUMINUM I BELIEVE

I know this one is not aluminum because a magnet sticks to it. Although alot of those brackets are cast alum. Anyways problem is solved I just bolted to it instead of welding. Thanks for your help, John

yea it is tappable and that works very nicely, if you want to make it sit perfectly can face the hole and make it truely flat.