Rare earth magnets generally apply to a magnet called Alnico. Alnico magnets are very expensive and can be found inside of harddrives among many other items. They are very strong…and also very expensive to buy.
What is inside of one? Aluminum, Copper, Cobalt, Titanium, and Iron. All of these put together at the correct temperature and percentages make up one of the strongest magnets that you will ever see. These are commonly mistaken to be the magnets found in speakers, but those magnets are almost always ceramic and are worth no money…but are GREAT for using to check whether or not something sticks and if it is ferrous or non-ferrous.
Hope this helps, scrap ya later!
*Bonus Scrap Tip* If you use the magnets from speakers for checking steel and other ferrous items when scrapping (magnet sticks to ferrous metals), you can also use it to keep your workplace next and tidy. If you connect the magnet to the end of a broomstick you can collect the little nuts, bolts, nails, and screws that you have around from taking items apart. You can then put them all in a bucket together to scrap them when the bucket is full. You won’t believe how much weight in nails and bolts you will collect over time.
*Extra Bonus Scrap Tip* When you are using the magnets to collect nails and bolts, you can place a piece of saran wrap around the outside so that you can just pull it right off when you want to take the nails and bolts off. It’s a quicker way of working and cleaning up and it can give you more time to scrap.