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FAQs

What is a mineral?
Is a rock a mineral?
What is a crystal?
What is a gemstone?
What is a geode?
Where can I find answers to other questions?

 

What is a mineral?
A mineral is an inorganic naturally-occuring crystalline solid. It has specific physical properties and a definite chemical composition. Please read How to Identify Minerals for a description of some of the basic physical properties of minerals.

 

Is a rock a mineral?
No. Although a rock is also inorganic and occurs naturally, it is not a crystalline solid. It is a consolidated material composed of grains of one or more minerals.

 

What is a crystal?
A crystal is a geometric solid that forms in a definite, repeating pattern. The external shape of the crystal is smooth and symmetrically arranged, reflecting the internal arrangement of its atoms.

 

What is a gemstone?
A gemstone is any rock, mineral, or other substance used for adornment. A gemstone has three qualities that separate it from other materials: rarity, beauty, and durability. Rarity and beauty increase its value. Durability, or hardness, ensures the gemstone will last through time. Some minerals, such as diamond, garnet, and beryl are gemstones.

 

What is a geode?
A geode is a hollow, rounded rock. The hollow is usually filled with crystals, like quartz or agate. A geode begins as a bubble in volcanic rock or a hollow in sedimentary rock. Eventually, the outer shell hardens. Minerals begin to precipitate and over thousands of years, many layers of crystals form inside the geode.
For more, read Geodes, an article by Lynn M. Bremner of Desert USA.

 

Where can I find answers to other questions?
Continue exploring Mineral Matters.
Read about Regional Minerals in our Field Guide to the Californias.
If you're an advanced reader, see our Mineralogy Department FAQs.
Or, you can ask our researchers.



Mineral Matters | Kids' Habitat

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