What would make Brass magnetic?

A. I think you are clutching at straws. Copper and zinc are the components of brass; if it contains iron of any degree that would make it magnetic, you have cheap second rate brass.

A. Stumbled on this thread and thought I'd toss my answers into the mix from a metallurgical perspective. First of all, non-ferrous doesn't mean that a material contains 0.0% iron, only that it is not iron based. Brass alloys are classified as non-ferrous because they are copper based. Brasses are primarily alloyed with zinc, but can also contain tin, manganese, nickel, lead, and iron. Iron and nickel are both ferromagnetic, manganese is paramagnetic.
Secondly, Neodymium magnets are very strong. If you had an iron based substrate that was brass plated, the magnet would have a strong attraction right through the plating.
Thirdly, the fact that the magnet is very strong means that it will be weakly attracted to very small amounts of magnetic material in the brass. I have a known sample of a copper base alloy, SAE 430B, sitting on my desk right now that has a neodymium magnet stuck to it. SAE 430B contains 2 to 4% iron, and the magnet has a fairly strong attraction (strong enough to hold 3 business cards in place).
Bottom line is I believe you have a vase that was made from a brass alloy that contains some small percentage of iron and/or nickel.

A. Actually, WikiAnswers says that brass may contain 0.2 - 0.4% iron as an ordinary contaminant - and that's enough to get a noticeable attraction from o Neodymium-based 'super-magnet'. all of the 'commercial grade' brass bar that I've played with will be weakly attracted to a super-magnet.

A. You said you used a neo magnet, which is one of the stronger magnets. It did not "stick" to it in the sense of a true ferrous metal would be attracted to a magnet, But the neo magnet creates an electro field in line with the falling (gravity works) of the magnet which can if the magnet is strong enough seem to be magnetic. This is only a force of force created by the electrons in the brass only slightly trying to line up with the N and S poles of the neo magnet, thereby not "sticking" to the non ferrous metal but trying. In theory if the size of the neo magnet was so large in comparison to a relatively small piece of brass, it would stick.
Or perhaps another scenario posted by others could be correct.

A. Jim, I think you are right. I have found that a neo magnet will be attracted to plated or painted steel almost as strong as bare steel. A couple years ago I bought some cheap brass fluid fittings on eBay. I noticed a neo magnet had a weak attraction to them. I ground into one and found that there was no color change throughout the cross section. I tried a magnet on some higher quality brass and found no attraction. After doing some research I found that a small amount of iron is permissible in brass alloys. I suspect that cheap brass has higher iron content than higher quality brass. I agree with you that this is likely causing the weak attraction of a magnet.

A. Could be aluminum bronze which looks very similar to Brass or even gold that often contains small amounts of iron.
This and other alloys are typically referred to as copper alloys instead of brass or bronze so as not to cause so much confusion.

Aluminum Bronzes are copper-base alloys containing 6% to 12% aluminum and varying amounts of iron, nickel, manganese and/or silicon alloying additions that provide a broad range of mechanical properties -- from high ductility to the high-strength levels of high-tensile manganese bronze.

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