Meteorwrongs: rocks that fool people

Lots of people find a strange rock and hope it is a meteorite. Most turn out to be meteorwrongs. Learning about them makes you a much better detective.

What is a meteorwrong?

A meteorwrong is a rock or object that people think is a meteorite, but is not. The name is a joke: meteorite sounds like meteor-right, so a mistake is a meteor-wrong.

Meteorwrongs are extremely common. Museums receive many rocks every year from people hoping they have found a space rock, and nearly all of them come from Earth. That is not surprising. Meteorites are rare, while ordinary rocks are everywhere.

Do not be disappointed if your rock is a meteorwrong. Every expert has looked at hundreds of them. Learning why a rock is not a meteorite teaches you a lot about geology, the science of Earth's rocks. Each meteorwrong is a chance to practise looking closely, which is exactly what scientists do every day.

The usual suspects

Here are some of the most common meteorwrongs.

Slag is the glassy, bubbly waste left over from making metal in furnaces. It can be heavy and dark, and sometimes magnetic, but it is usually full of holes.

Magnetite and hematite are iron minerals found in Earth's rocks. They are heavy, and magnetite is strongly magnetic. Rubbing hematite on the back of a tile leaves a red-brown streak, and magnetite leaves a black one, while most meteorites leave little or no streak.

Basalt is dark volcanic rock. Some pieces are smooth and black and look a bit like fusion crust.

Flint nodules and concretions are lumpy rocks that form inside layers of rock. They can have odd shapes and dark rinds.

Rusty bits of old machinery can fool people too!

Thinking like a scientist

Good meteorite detectives ask several questions, not just one. Is it heavy for its size? Does it attract a magnet? Does it have a thin, dark crust? Is it free of bubbles and holes? Does the inside show tiny metal specks or small round beads?

A rock that passes all of these tests might be worth showing to an expert. A rock that fails several is almost certainly from Earth.

Never try to break, cut, heat or put chemicals on a rock to test it. You could hurt yourself and you might ruin something important. If you think you have found a meteorite, ask an adult to help you contact a natural history museum or a university geology department. Remember to write down exactly where you found it.

Did you know?