Earth Minerals
Rocks and minerals are the building blocks of our dynamic planet. They form the landscape and provide us with valuable resources. By studying rocks and minerals we can better understand the events that shaped and continue to shape the Earth. Minerals are naturally occurring chemical compounds that have been formed by geological processes. Minerals also provide chemicals that are essential for life on Earth.Most rocks are mixtures of different minerals. They show remarkable variations in texture and composition, depending on how they formed. The colours shown by minerals span the visible spectrum – and beyond. A mineral’s colour sometimes comes from its essential chemical composition, for example, the striking green colour of dioptase is caused by copper. Other factors that colour minerals are small chemical impurities or defects in their crystal structure. A single mineral may show a range of colours. This usually arises from the effects of small amounts of ‘foreign’ atoms among the main ingredients of the mineral’s crystal structure. For example, fluorite (calcium fluoride) can be purple, green or yellow because of traces of different elements.