Geology

Learn about geology. Topics include minerals, Earth science, volcanoes, rocks, and important geological cycles.

Tropic of Cancer and Capricorn — Learn about the Tropic of Cancer and Tropic of Capricorn. Discover how they got their names, their latitude values, and other fun facts.

Tropic of Cancer and Tropic of Capricorn

This entry was posted on June 20, 2023 by Anne Helmenstine (updated on November 4, 2023)

Why Is the Ocean Salty — Learn why the ocean is salty but rivers and most lakes are not. Also, see whether the sea is getting saltier over time.

Why Is the Ocean Salty but Lakes and Rivers Are ...

This entry was posted on June 3, 2023 by Anne Helmenstine (updated on June 13, 2023)

Synthetic or Lab-Grown Diamonds — Learn about synthetic or lab grown diamonds, including how they form and how to tell them apart from natural diamonds.

Synthetic or Lab Grown Diamonds

This entry was posted on April 4, 2023 by Anne Helmenstine (updated on April 8, 2023)

What Is a Mineral - Definition and Examples — Learn what a mineral is in geology and other sciences. Get the mineral definition and examples and learn about mineral properties and types.

What Is a Mineral? Definition and Examples

This entry was posted on January 29, 2023 by Anne Helmenstine (updated on February 5, 2023)

Types of Lava Pahoehoe Aa — Learn about the types of lava including the forms of lava flow (pahoehoe and a'a) and the chemical composition based on silica content.

Types of Lava – Pahoehoe and A’a

This entry was posted on October 26, 2022 by Anne Helmenstine (updated on October 1, 2023)

Sea Glass and Beach Glass — Learn about sea glass and beach glass. See how they form, the colors and their rarity, and how to tumble glass yourself.

Sea Glass and Beach Glass

This entry was posted on July 12, 2022 by Anne Helmenstine (updated on July 18, 2022)

Gem vs Mineral — Learn the difference between gems and minerals. See examples of gemstones and their minerals. Explore precious and semiprecious gems.

Gem vs Mineral – Difference Between Gemstones and Minerals

This entry was posted on June 11, 2022 by Anne Helmenstine (updated on January 29, 2023)

Difference Between Rocks and Minerals — Learn the difference between rocks and minerals. Get their definitions and examples and also learn about mineraloids.

What Is the Difference Between Rocks and Minerals?

This entry was posted on May 28, 2022 by Anne Helmenstine (updated on July 9, 2023)

Layers of the Atmosphere — Learn about the 5 main layers of the atmosphere and also the sublayers. See the height, temperature, and composition of the layers.

Layers of the Atmosphere

This entry was posted on May 3, 2022 by Anne Helmenstine (updated on April 1, 2023)