How can I tell if it's cast Iron

Hi, all.

Over the last couple of years I've bought a bunch of material for one project or another. Most are still on the drawing board and I've lost track of quite a few of them.

One thing that's left me with is some metal whose purpose I no longer recall - if, indeed, I bought it for something in particular and not just because it might come in useful someday.

There's a block I will use for some bearings if it's cast iron - and not if it isn't.

How do I tell?

I thought I could scrape a bit - steel seems sticker to me than cast iron, but this wasn't conclusive. I can probably try and machine some. My experience is that cast iron comes of as grit and steel as streams or chips.

Is this reasonable accurate? Is there any easy way of doing this?

Thanks

Iain

Put it against your bench grinder, if grey CI then you will get dull red sparks

File it; if CI it will produce grey dust.

George.

Turning or milling will easily discern between the two - like the filing suggestion, by mechman48

I can usually tell when I am working with cast iron because it smells what I can only describe as earthy. Most other materials don't have such a distinctive smell.

Martin C

I'm glad I've heard someone else say it! I'd never have admitted it myself otherwise. It does have a distinctive smell.

Easy - if you're married......

Machine, file, emery or whatever the metal then wash your (black) hands in the domestic sink.
Next morning if you are subject to dog's abuse for all the minute rust stains on the sink's surface, it was cast iron.

Grinder dull red sparks -cast iron

bright yellow - steel