A magnet cannot pick up brass. Brass is a common metal alloy, often used in hardware and decorative items, and is fundamentally classified as a non-magnetic material. This lack of attraction is the direct result of the metal’s atomic structure and chemical composition. Understanding why requires a brief look into the physics of how materials interact with a magnetic field. This explanation reveals why some metals stick strongly to a magnet while brass exhibits no noticeable response.
The Science of Magnetic Attraction
Strong magnetic attraction is governed by a phenomenon called ferromagnetism. Ferromagnetic materials, which include iron, nickel, and cobalt, have unpaired electrons that cause their atoms to act like tiny, permanent magnets. These atoms naturally group together into microscopic regions called magnetic domains. When a magnet is brought near a ferromagnetic material, the external magnetic field forces these domains to align in the same direction. This alignment creates a powerful, temporary internal magnetic field that results in the strong attraction observed. Most metals lack this specific atomic structure and therefore do not possess magnetic domains that can be aligned by a household magnet.
Brass Composition and Magnetic Classification
Brass is an alloy primarily composed of copper and zinc, with the ratio varying depending on the specific type. Copper typically makes up 60% to 90% of the alloy, while zinc accounts for most of the remainder. Neither of these constituent elements is ferromagnetic, which is the foundational reason brass is non-magnetic. Pure copper and pure zinc are classified as diamagnetic elements, meaning they are very weakly repelled by a magnetic field. Therefore, brass itself is considered diamagnetic or, in some variations, very weakly paramagnetic, which results in a negligible response to a standard magnet.
Practical Applications and Common Exceptions
The non-magnetic nature of brass is a highly valued property in many engineering applications. Because it does not interfere with magnetic fields, brass is frequently used in sensitive electrical components, marine hardware, and musical instruments. Its resistance to corrosion and magnetic neutrality makes it suitable for parts used near the ocean or where magnetic interference must be avoided.
People occasionally report finding brass objects that stick to a magnet, which is almost always due to one of two common exceptions. The first is trace impurities, most often iron, introduced during manufacturing or recycling. Even small amounts of this ferromagnetic contaminant can cause a weak, localized magnetic response. The second common cause is plating, where a highly ferromagnetic base metal like steel has been coated with a thin layer of brass for appearance.