 Would you be surprised if I told you that some minerals are magnetic? Maybe even more surprising is if I told you that all materials are magnetic. Is a strawberry magnetic? Yes it is. If you place a strawberry in a very strong magnetic field it will hover in the air. In this video we can see a strawberry hovering inside a strong magnetic field and when I say strong I mean 200,000 times bigger than the Earth's magnetic field. The reason it floats is because it's full of water and water is magnetic but we have to remember water is very weakly magnetic. That's why we need such a strong magnetic field. So if we can agree that even strawberries are magnetic then maybe it's not such a big surprise that minerals, in particular those containing iron are magnetic too. I'm going to talk about hematite which is an iron oxide Fe2O3 and compared to most minerals it's strongly magnetic and we can actually identify its properties using a specialized instrument called a magnetometer. Now hematite is a slightly strange word. Where does it come from? Well hematite comes from the Greek word for blood and if you think about hemoglobin in your blood which you've probably learned about in your biology lessons, it's bright red. So hematite has this deep red colour because it contains a lot of iron just like the hemoglobin in your blood. Now let's think about the dusty red centre of Australia. When you think about that you're thinking about hematite. Hematite forms due to weathering in these really dry environments like the red centre of Australia and it's hematite that gives that distinctive red colour to the dust in these areas. Now living in Australia you've probably seen pictures or even experienced a dust storm. For example we had a really big one that moved through Sydney a few years ago and when you look at a photograph of the Sydney Harbour Bridge you'll see this red dust surrounding everything. That's hematite. So we often see these pictures of dust storms producing red and orange skies but what happens to all of that dust? The wind blows some of the dust out to sea and these particles can be transported very long distances across the oceans. For example look at this image of an orange dust storm heading out from Western Australia. We can see it's huge. There is a massive amount of dust being blown across the ocean. In the video you're looking at now we've seen an image of the 2020 Godzilla dust storm. It's actually a collection of satellite images that have been put together. So this dust storm was so big we could even see it from space and what it's showing is dust rich in hematite and girtite being blown from the Sahara Desert all the way across the Atlantic. But while this dust is travelling around the world some of the particles land on the surface of the ocean. They sink through the water and incorporated into the sediment on the sea floor. This process has been happening around the world for millions of years and reflects the environmental conditions. Dry conditions mean we have more dust storms and therefore more hematite is blown into the air and deposited into the oceans. As part of our work at A&U we use really big research ships to core sediments from the world ocean. These sediments span millions of years through geological time. We then use the magnetometer that I told you about earlier that can measure really weak magnetic materials to measure how much hematite we have in different parts of the sediment core that represent different periods of geological time. More hematite in the sediment suggests that more dust was being transported over the oceans by the wind. Therefore more hematite means we infer that the environment was cold and dry. Less hematite means that we infer that the environment was warmer and wetter and there was less dust transport.