Rock and mineral collecting is a fascinating hobby which can be shared by the entire family. Before you get started with your new hobby it is important to understand something about minerals.
Rocks are made up of one mineral, or a mixture of minerals. Minerals are made up of elements, which are simple substances which cannot be broken down into any other substance. Sometimes minerals are made of only one element, but most minerals are made up of two or more elements. Many minerals are made up of a large number of elements.
Minerals are often found as shapeless lumps. These pieces are called "massive". Some minerals can also form special shapes, which can help you to identify them.
The mineral is said to "grow" when the elements that the mineral is made of gets built up in layers on the mineral's outside surface. Minerals grow into all kinds of rough shapes in the spaces between other minerals around them. If a mineral can grow freely, such as on the sea bed, or in the hole of a rock, it may form beautiful crystals.
Minerals also form other shapes which are not crystals. The mineral smithsonite forms rounded crusts on rocks and minerals. Pyrite may form smoothly rounded lumps called nodules.
If you find a mineral with perfectly flat surfaces, it is likely a crystal. Some minerals break cleanly when hit, leaving pieces with smooth surfaces that look like crystals.
These clean breaks are called "cleavages". Each mineral tends to break or cleave more easily in some directions than in others. The way it breaks is called its cleavage pattern. Often you can identify minerals by a combination of their crystal shape and their cleavage pattern.
Related Internet resources:
http://toyscollectibles.allinfo-about.com/features/minerals.html
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