Petrified Wood is a fossil that forms when dissolved material preciptates and replaces wood.
Iolite is the gem variety of the mineral cordierite. An alternative to sapphire and tanzanite.
Azurite Granite ? A white granite with blue orbs of azurite. A new material from Pakistan.
Sliding Rocks Mystery - What causes these rocks to slide across a playa in Death Valley?
|Great Rift Valley
The East Africa Rift System - The extensive fault system that is tearing Africa apart.
||Crater of Diamonds
Crater of Diamonds - The only diamond mine in the world where you can be the miner.
||What are Glaciers?
What are Glaciers? Learn how glaciers form, flow, advance, retreat, and change over time.
Geology Tools - Rock hammers, field bags, hand lenses, maps, hardness picks, gold pans.
Geology.com News is updated several times each week. Read it here or receive email updates.
Rocks - Galleries of igneous, sedimentary and metamorphic rock photos with descriptions.
||US Diamond Mines
US Diamond Mines - Did you know that diamonds have been mined in the United States?
Yosemite Glaciers There are two active glaciers in Yosemite - but they are slowly melting away.
Tanzanite was unknown until a few decades ago but it has erupted into wide popularity.
||Oil Fields from Space
Oil Fields from Space - Night views of Earth show the distribution of oil field activity.
||Fireworks & Minerals
The Science of Fireworks Their shapes and colors - produced through chemistry, physics & art.
||San Andreas Fault Map
Google Map of the San Andreas Fault Zoom in to see the fault trace on satellite images.
|Coal Close Up
Coal Through a Microscope - Coal is more than a black rock. It is THE most interesting rock.
Mount Cleveland is an active volcano in the Aleutian Islands and a threat to air traffic.
Minerals - Descriptions, photos, articles, properties and uses for common minerals.
||Arctic Seafloor Map
Arctic Ocean Seafloor Map The ridges, basins, shelves and rifts defining the Arctic seafloor.
The Host Rock of Diamonds - Diamonds are found in Kimberlite, a variety of peridotite.
California Earthquake Maps A collection of isoseismal maps for earthquakes in California.
||Sea Level Rise Maps
Sea Level Rise Maps - See what will be flooded as sea level rises.
||Find Minerals & Gems
Find Minerals and Gems - Dozens of sites where you can dig and keep what you find.
|Life on Europa ?
Life on Europa might exist in a salty ocean a short distance below its frozen surface.
Volcanic Explosivity - Rating volcanic eruptions based upon the volume of tephra ejected.
Sunstone is a gem feldspar with aventurescence caused by light reflecting from platy inclusions.
||Lightning Strikes Map
Lightning Strikes Map - A NASA map showing the worldwide distribution of lightning activity.
Mineraloids are amorphous naturally-occurring inorganic solids that lack crystallinity.
||Oil and Gas
Oil and Gas - Articles about oil and natural gas in the US and around the world.
Meteorite Identification Step one in identifying a possible meteorite is the magnet test.
Mount Vesuvius - geology, history, maps, facts and more about the Vesuvius eruptions.
Bear Attacks - Knowing how to react to a bear encounter or attack could save your life.
||The Brewery Rock ?
The Rock Used to Make Beer - Geologists are beer experts and should know about this rock.
Help a Science Teacher - At DonorsChoose.org you can support a K-12 science project.
||Google Earth - Free
Free Google Earth software allows you to browse seamless world satellite images. Free.
Gemstones - Colorful images and articles about diamonds and colored stones.
Lapis Lazuli - a metamorphic rock and the most popular blue opaque gemstone in history.
Pictures of Opal - A collection of different types of opal from all around the world and Mars too!
Diamonds - Learn about the properties of diamond, its many uses and diamond discoveries.
|Asteroid Impact Map
Asteroid Impact Map - Explore fifty of the most obvious asteroid impact craters on Earth.
Dowsing is a method used to find underground water that is rejected by most geologists.
Fluorescent Minerals and rocks glow with spectacular colors under ultraviolet light.
||Land Below Sea Level
Land Below Sea Level - Did you know that dozens of land locations are below sea level?
|San Andreas Fault
The San Andreas Fault - A feature that separates the Pacific and North American Plates.
Rhodonite - a manganese silicate used as a minor ore of manganese and as a gemstone.
Obsidian - the volcanic rock that cools so quickly that it becomes a natural glass.
100+ Gems - Photos of over 100 beautiful gems ranging from the popular to the obscure.
|Watch out for Ticks!
Ticks are a problem for geologists in some areas. Learn to recognize and avoid them.
Plate Tectonics - Articles, maps, information about plate tectonics and the interior of Earth.
Diamond Misconception - Lots of people think that diamonds form from coal. Not True!
Emerald is the most popular green gemstone in the United States and most of the world.
Tallest Tsunami - A wave with a run-up height of 1720 feet occurred in Lituya Bay, Alaska.
Crushed Stone - About four tons per person is used each year in the United States.
Fossils - Learn about fossils and discoveries around the world.
||The Acid Test
The Acid Test - Geologists use dilute hydrochloric acid to identify carbonate minerals.
Turquoise - A bluish-green gem material that has been used for over 6000 years.
Teacher Resources - K-12 resources for teaching about earth science.
||Gems from Space
Extraterrestrial Gems - A number of materials from space are used as attractive gems.
||What Is The Moho?
What Is The Moho? Learn about the Mohorovicic Discontinuity - the mantle/crust boundary.
Mohs Hardness Scale is a set of reference minerals used for classroom hardness testing.
Ammolite is a fossil and a gemstone. It is shell material from fossil ammonites.
Methane Hydrate deposits contain more fuel value than all other fossil fuels combined.
||Uses of Marble
The Uses of Marble are numerous and diverse. You will be surprised by how it is used.
|What Is Earth Science?
What Is Earth Science? The study of Earth and its neighbors in space. Learn more!
||Huge Diamond Deposit
The Largest Diamond Deposit in the world could be under Popigai Crater in Russia.
Homeowners Insurance usually does not cover the most common geologic hazards.
Exploring a Hydrocarbon Sea on Titan with a submarine is a potential NASA mission.
Corundum is the third hardest mineral. It is also the mineral of ruby and sapphire.
||Cave of the Hands
Cave of the Hands is a cave where ancient people painted hands about 9000 years ago.
Rock Art - People have been marking on rocks for thousands of years.
Labradorite is a feldspar mineral that sometimes exhibits an iridescent play-of-colors
Astronomy - Fantastic images and articles about solar system and deep-space astronomy.
||What is Geology?
What is Geology? - The study of Earth materials, structures, processes and life over time.
||Rare Earth Elements
Rare Earths - Special materials used in electronics, defense, medical & many other products.
Metals are important mineral products used in manufacturing and construction projects.
|Facts About Copper
Facts About Copper - Information about copper uses, production, resources and more.
Largest Desert - The Sahara is huge but two polar deserts are larger.
Largest Earthquake ever recorded - Magnitude 9.5. Chile, 1960.
Meteorites - Rocks that were once parts of planets or large asteroids.
|Ruby and Sapphire
Ruby and Sapphire are the 2nd and 3rd most popular colored stones in the United States.
Horizontal Drilling has opened new resources and significantly improved productivity.
Soapstone is a metamorphic rock with properties that make it suitable for a variety of projects.
||What is a Geyser?
Photos of Geysers from around the world with information about height, eruption interval, more.
Granite - The intrusive igneous rock that underlies continents and countertops.
Sand is a diverse material. This gallery includes photos of sand from around the world.
||USA Landslide Map
Landslide Incidence Map - A USGS map showing landslide incidence in the United States.
Volcanoes - Articles about volcanoes, volcanic hazards and eruptions past and present.
Ametrine is a bicolor quartz (amethyst + citrine) and a gemstone of growing popularity.
||Volcanoes in Space
Extraterrestrial Volcanoes - Earth is not the only solar system body with volcanoes.
Chatoyant Gems look like the eye of a cat. A line of light moves across the surface of the stone.
Tallest Mountain - Everest has rivals in tallness, altitude and distance to the center of Earth.
|What is LNG?
What is LNG? The use of LNG as an energy source is growing rapidly. Learn more about LNG.
Limonite - an amorphous iron oxide. Used as an iron ore and pigment since prehistory.
Garnet is best known as a red gemstone. It occurs in any color and has many industrial uses.
Hematite - The most important ore of iron. A source of mineral pigment since prehistory.
|Uses of Gold
The Many Uses of Gold - Unique properties make gold one of the most useful metals.
Shale - The rock that has quickly transformed the oil and gas industry.
Rock Glaciers - Masses of rock, ice, snow, mud and water that slowly flow down slope.
Hydraulic Fracturing - Increases well yield by fracturing the reservoir rock with fluid injection.
|Types Of Eruptions
Types of Volcanic Eruptions - A description of the most common eruption types.
Frac Sand - The amount of frac sand produced in the USA is up by over 300% since 2009.
Largest Volcano - That title is shared by Tamu Massif, Mauna Kea and Ojos del Salado.
Basalt - Most of the ocean basin and part of the continents are underlain by basalt.
Salt Domes - Columns of salt that move upwards because of their low specific gravity.
||Rocks on Mars
Rocks on Mars - Many of the rocks found on Mars are not very different from Earth rocks.
Mount Etna - The most active volcano in Europe continues an eruption that started in 2001.
||Yosemite Rock Fall
Yosemite Rock Fall Photos A photo sequence of a rockfall and debris avalanche by Herb Dunn.