There are lots of types of rock and each type has different properties and uses. For example, some are strong and hard but others are soft and sandy. Some rocks are harder than others. For example ...

The rocks on Earth are constantly changing due to many different processes. There are three main types of rock, with rocks changing between each type over millions of years. This rock recycling is ...

Although these measures were not all developed for stones, they have been adapted to allow for measurements of fine-grained rocks.” All kinds of different stones were included in the study ...

The discovery of pale, loose rocks on the Martian surface could suggest that Mars was once a much warmer world.

Rocks loafing about on the surface of Mars have been harboring secrets about the red planet's mysterious past.