Rocks

The Himalayas stand as Earth’s highest mountain range, possibly the highest ever. How did it form? Why is it so tall? You might think understanding big mountain ranges requires big measurements – perhaps satellite imaging over tens or hundreds of thousands of square miles. Although scientists certainly use satellite data, many of us, including me, study the biggest of mountain ranges by relying on the smallest of measurements in tiny minerals that grew as the mountain range formed. These minerals are found in metamorphic rocks – rocks transformed by heat, pressure or both. One of the great joys in studying metamorphic rocks lies in microanalysis of their minerals. With measurements on scales smaller than the thickness of a human hair, we can unlock the age and chemical compositions hidden inside tiny crystals to understand processes occurring on a colossal scale. Measuring radioactive elements Minerals containing radioactive elements are of special interest...

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to curiouskidsus@theconversation.com. How do crystals form? – Alyssa Marie, age 5, New Mexico Scientifically speaking, the term “crystal” refers to any solid that has an ordered chemical structure. This means that its parts are arranged in a precisely ordered pattern, like bricks in a wall. The “bricks” can be cubes or more complex shapes. I’m an Earth scientist and a teacher, so I spend a lot of time thinking about minerals. These are solid substances that are found naturally in the ground and can’t be broken down further into different materials other than their constituent atoms. Rocks are mixtures of different minerals. All minerals are crystals, but not all crystals are minerals. Most rock shops sell mineral crystals that occ...

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to curiouskidsus@theconversation.com. Why don’t rocks burn? – Luke, age 4, New Market, New Hampshire While many rocks don’t burn, some of them do. It depends on what the rocks are made of – and that’s related to how they were formed. There are three main rock types: igneous, sedimentary and metamorphic. These rocks are made of minerals that all have different characteristics. Some will melt into magma or lava – super-hot, liquid rock – when they are exposed to heat. Others will catch fire. Rocks can look alike, but one rock is not like another. Rocks that burn when they get heated up are combusting. This means that elements within the rocks are reacting with oxygen in the air to produce heat a...