ferrous metal, scrap metal

The Science Behind Scrap Metals

Read Time: 4 minutes

There is a science behind scrap metals, and in more than one connotation of the word. Scrap metals are quite literally a goldmine, as well as a steel, aluminum and copper mine. People who profit from scrap metals are not only engaging in a rewarding and fascinating hobby, but are also financially profiting from it — sometimes enough for it to be their sole income. Moreover, the scrap metal industry is a serious contributor to the worldwide recycling effort, and its effects on sustainability are not insignificant.

So what exactly do you do with scrap metals to make it worth your time?

Scrap metals can be found almost anywhere, whether in your home, in the trash or in a garden. The more you work with them, the easier it will become to spot the valuable metal components. Some of the most commonly monetized and sought-after metals found in scrap are the following:

  • Aluminum
  • Brass or bronze
  • Copper
  • Gold
  • Lead
  • Steel

You now have piles of scrap metal, and they all look the same. Nonferrous metals tend to be valued higher than ferrous metals, so it’s imperative to learn how to differentiate between the two.


A magnet is your best friend from here on in. Ferrous metals, including iron and steel, are magnetic. They can be sold together, since steel is made up of carbon and iron predominantly. Naturally, that means nonferrous metals are nonmagnetic, so you should have two separate piles by the end of the first stage.


Let’s be optimistic and assume you will be finding decent quantities of at least six different metals from your initial collection. Dividing them up once properly identified is imperative to the smoothness of your interaction with the scrap metal dealers and will affect how much you receive in exchange.

As part of your foraging efforts, you will likely come across unused large containers or bins. Label each one aluminum, brass or bronze, copper, gold, lead or steel.

Sight Sort

A keen eye for color will help you identify nonferrous metals.

Aluminum is an easy one in that it is unmistakably light and usually found in the form of soda cans with a silver color. Another helpful indicator is that it will not rust.

Brass and bronze are copper alloys. They will be yellow-colored as opposed to golden, and most commonly can be found in musical instruments, ornamental pieces and pipe valves. You can expect to get about 50 percent of the value of pure copper, as it is a copper alloy.

Copper is copper-colored and can be found in cookware, electronics and wiring in the form of wires, pipes and cables. Tarnished copper will be brown or red, while oxidized copper will be green — think of every building-top in Paris! Copper wire is pure, therefore most valuable and contains a purity level between 75 to 85 percent. Anything less will be found in extension cords (50 percent purity) or Christmas lights (15 percent purity).

Gold will obviously be golden in color. When compared to brass, the brass will seem far more yellow. There are certain caveats to watch out for when identifying the true purity of gold — or karats — so it’s worth investing in proper testing kits. These kits use testing acids to properly identify the gold’s actual purity.

On to the ferrous metal identification:

Lead is most likely the heaviest metal you will find among your scrap collection, and it has a density of 150 percent more than iron. You will know from your pencil-writing school days that it is soft enough to be engraved with a sharp tool and also that it is very toxic. Lead can be used in X-ray machines as well as in the ammunitions industry.

Steel is extremely solid and strong and if not stainless, it most likely will be rust-colored. Stainless steel comes in a number of different varieties, and in its basic form it will remain magnetic. However, many stainless steel varieties that have higher chromium content and nickel — known as austenitic — therefore the magnetic test will not work here. There should be far less occurrence of rust, if any, on your stainless steels, so it shouldn’t be hard to identify.

There is another commonly used identifying test known as the spark test. This tends to involve a little more equipment and effort on your part, but is undeniably reliable if you are having issues with the magnetic and sight methods.

One last thought: Be sure to give your metals a good scrubbing when possible and appropriate. Clean scrap is worth more than those covered in mud, rust and other contaminants. Otherwise, you’re ready for the most rewarding and exciting part of your scrap metal endeavor, which is exchanging it for payment at your local recycling yard.

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Category: Chemistry


  1. I like what you said about the importance of organizing your scrap metal. I think that recycling copper is a great way to save the environment.

  2. I appreciate the way you broke down different kinds of scrap metal. My wife and I have found a fair amount of it in the desert and were wondering what to do with it. I think we’ve found 6 or 7 different kinds, so we should be able to recycle at least some of it. Thanks for the tips!

  3. Thanks for helping me learn more about scrap metal. I actually didn’t know that is beneficial to organize and divide the different kinds of metals, and that it can help the scrap metal dealers by doing this. Maybe the dealers could also provide some advice on organizing the metals, like how they should be gathered and transported.


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Article by: Megan Ray Nichols

Megan Ray Nichols is a freelance science writer and science enthusiast. Her favorite subjects include astronomy and the environment. Megan is also a regular contributor to The Naked Scientists, Thomas Insights, and Real Clear Science. When she isn't writing, Megan loves watching movies, hiking, and stargazing.