Largest Volcano - That title is shared by Tamu Massif, Mauna Kea and Ojos del Salado.
Herkimer Diamonds Doubly-terminated quartz crystals used as specimens and gems.
What Is Earth Science? The study of Earth and its neighbors in space. Learn more!
Gem Silica is a blue chalcedony colored by copper. It is the rarest and most valuable chalcedony.
Chalk is a variety of limestone formed from fine-grained marine sediment known as ooze.
Olivine - Abundant in Earth*s mantle. A constituent of meteorites. The gem peridot.
Hawaii*s Next Island could be growing in the Pacific Ocean right now. Its name is Lo*ihi.
Coal Through a Microscope - Coal is more than a black rock. It is THE most interesting rock.
World*s Largest Diamonds Records for the largest rough, faceted and carbonado diamond.
Minerals - Descriptions, photos, articles, properties and uses for common minerals.
Talc is a soft mineral used in cosmetics, paper, paint, ceramics and many other products.
Rocks - Galleries of igneous, sedimentary and metamorphic rock photos with descriptions.
100+ Gems - Photos of over 100 beautiful gems ranging from the popular to the obscure.
The Unsung Mineral Hero - and the commodity upon which almost everything is built.
The Doorway to Hell is a flaming sinkhole seeping natural gas that has been burning for decades.
Homeowners Insurance might not cover earthquake, hurricane and other geohazard damage.
Plate Tectonics - Articles and maps about plate tectonics and the interior of Earth.
Wall Maps - Wall maps of the world, continents, states and the USA.
Free Google Earth software allows you to browse seamless world satellite images. Free.
Lapis Lazuli - a metamorphic rock and the most popular blue opaque gemstone in history.
Rock Salt is a sedimentary rock composed of the mineral halite. It has many uses!
Obsidian - the volcanic rock that cools so quickly that it becomes a natural glass.
Know the Rules before removing rocks, fossils or minerals from public or private property.
Grape Agate is a popular mineral specimen with the color and the shape of a bunch of grapes.
Granite - The intrusive igneous rock that underlies continents and countertops.
Birthstones are gems assigned to the month of a person*s birth. They are popular gifts in the U.S.
Emerald is the most popular green gemstone in the United States and most of the world.
Diamonds - Learn about the properties of diamond, its many uses, and diamond discoveries.
Rhyolite An extrusive igneous rock with a high silica content, produced from granitic magma.
Types of Maps - Explore some of the most popular types of maps that have been made.
The Rock Used to Make Beer - Geologists are beer experts and should know about this rock.
Gemstones - Colorful images and articles about diamonds and colored stones.
Cave of the Hands is a cave where ancient people painted hands about 9000 years ago.
Chalcopyrite - The most important ore of copper for over five thousand years.
Rock & Mineral Kits The best way to learn about rocks and minerals is with specimens!
Rocks on Mars Many of the rocks found on Mars are not very different from Earth rocks.
Meteorites - Rocks that were once parts of planets or large asteroids.
The Green River Formation is one of the most famous rock units in the world for its fossils.
Waterproof Paper - Don't take chances with your field notes and maps. Use waterproof paper.
Hardness Picks - Test for hardness with precise and easy-to-use hardness picks.
Types of Volcanic Eruptions - A description of the most common eruption types.
Quartzite is metamorphic rock formed when sandstone is subjected to heat and pressure.
Hand Lens A 10-power folding magnifier in a metal case. A frequently used lab and field tool.
Fire Opal is a transparent to translucent opal with a yellow, orange or red background color.
Crater of Diamonds - The only diamond mine in the world where you can be the miner.
Ilmenite - The primary ore of titanium and source of most titanium dioxide.
Pictures of Opal - A collection of different types of opal from all around the world and Mars too!
Geology Books - A variety of books for reference, field trips, reading and more.
Portable UV Lamp - Short and long wave UV for fluorescent mineral viewing.
Volcanoes - Articles about volcanoes, volcanic hazards and eruptions past and present.
Labradorite is a feldspar mineral that sometimes exhibits an iridescent play-of-color.
Bear Attacks - Knowing how to react to a bear encounter or attack could save your life.
Debris Flows are moving masses of loose mud, sand, soil, rock and water.
Fool*s Gold is a name used for pyrite when its brassy color fools people looking for gold.
Gold Pans and Panning Kits - classifiers, snuffer bottles. Learn how to pan for Gold.
Gifts That Rock - What are the most popular gift items in the Geology.com store?
The Uses of Marble are numerous and diverse. You will be surprised by how it is used.
Fluorescent Minerals and rocks glow with spectacular colors under ultraviolet light.
Geodes look like ordinary rocks on the outside but can be spectacular inside!
Rare Earths - Special materials used in electronics, defense, medical & many other products.
Copper is a metal used in coins, electronics, pipes, wiring, motors, alloys and many other products.
Extraterrestrial Gems - A number of materials from space are used as attractive gems.
Precision Scale HO #33234 Sill, End Draft w/Coupler Carrier Bar, and the largest highly acidic lake in the world at Kawah Ijen Volcano.
Where Are the Canary Islands? Off the northwest coast of Africa, 60 miles west of Morocco.
Spatter Cones are small, steep, volcanic cones built of welded basaltic lava.
Rhodochrosite - a manganese mineral used as an ore, a pink gem and an ornamental stone.
Field Courses - Over 80 field courses for undergraduate geology students.
Andalusite is a metamorphic mineral and a strongly pleochroic gem material.
Tallest Tsunami - A wave with a run-up height of 1720 feet occurred in Lituya Bay, Alaska.
Ruby and Sapphire are the 2nd and 3rd most popular colored stones in the United States.
Ticks are a problem for geologists in some areas. Learn to recognize and avoid them.
Rock Art - People have been marking on rocks for thousands of years.
Turquoise - A bluish-green gem material that has been used for over 6000 years.
Names Used for Great Britain, British Isles, United Kingdom, and Ireland. What they mean.
The East Africa Rift System - The extensive fault system that is tearing Africa apart.
Geology Tools - Rock hammers, field bags, hand lenses, maps, hardness picks, gold pans.
Rock Tumblers - All about rock tumblers and rock tumbling. Read before you buy a tumbler.
Sand is a diverse material. This gallery includes photos of sand from around the world.
Mineral Rights - Who owns the minerals under your land? Who wants to buy them?
Diamond Misconception - Many people think that diamonds form from coal. Not True!
What Is The Moho? The Mohorovicic Discontinuity is the mantle/crust boundary.
The Science of Fireworks Learn how the colors and shapes are created.
Ant Hill Garnets - tiny gems that ants haul to the surface and discard on their anthill. Honest!
What Is Luster? Luster is the light-reflecting characteristics of a mineral specimen.
Expansive Soil causes more damage than floods, hurricanes & tornadoes combined.
Teacher Resources - K-12 resources for teaching about earth science.
Morganite is an orange to pink gemstone, a variety of beryl, that is growing rapidly in popularity.
Topo Maps - The DeLorme Atlas is an entire state of topo maps in one convenient book.
The Acid Test - Geologists use dilute hydrochloric acid to identify carbonate minerals.
Citrine is the transparent variety of quartz with a yellow to orange to reddish color.
Cinnabar - the only important ore of mercury. Used in pigments until its toxicity was realized.
Corundum is the third hardest mineral. It is also the mineral of ruby and sapphire.
Novarupta - The most powerful volcanic eruption of the 20th century occurred in the U.S.A.
Tanzanite was unknown until a few decades ago but it has erupted into wide popularity.
Ethiopian Opal - The new opal heavyweight that might give Australia a run.
World Record Lightning - this lake has more lightning than any other place in the world.
Helium is a byproduct of the natural gas industry. Its most important use is in MRI.
Mohs Hardness Scale is a set of reference minerals used for classroom hardness testing.
Map of the Oceans - showing the Atlantic, Pacific, Indian, Arctic, and Southern Oceans.
Mars Meteorites Mars rovers have found dozens of meteorites while exploring the red planet.
Zircon is the primary ore of zirconium and a gemstone that is available in many colors.
Tallest Mountain - Everest has rivals in tallness, altitude and distance to the center of Earth.
What is Geology? The study of Earth materials, structures, processes and life over time.
Mineraloids are amorphous naturally-occurring inorganic solids that lack crystallinity.
Shale - The rock that has quickly transformed the oil and gas industry.
Crystal Habit is the external shape displayed by a crystal or an aggregate of crystals.
Volcanic Explosivity - Rating volcanic eruptions based upon the volume of tephra ejected.
Sliding Rocks Mystery - What causes these rocks to slide across a playa in Death Valley?
Stub Axle Front Right / 16701276 For OPEL ASTRA J LIM. 2.0 16V C The power of a moving plate over a stationary hot spot.
Largest Earthquake ever recorded - Magnitude 9.5. Chile, 1960.
Largest Hurricanes Are they determined by wind speed, value of damage, most deaths?
Petrified Wood is a fossil that forms when silica replaces and infills the cavities of wood.
US Diamond Mines - Did you know that diamonds have been mined in the United States?
The Many Uses of Gold - Unique properties make gold one of the most useful metals.
Hematite - The most important ore of iron. A source of mineral pigment since prehistory.
Lightning Strikes Map by NASA shows the worldwide distribution of lightning activity.
Colored Diamonds are diamonds with a noticeable body color. They can sell for over $1M/carat.
What is a Maar? The second most common volcanic landscape feature on Earth.
Coquina - A porous limestone composed almost entirely of fossil debris.
Peridotite is a chromite host rock, a source of diamonds and a possible carbon dioxide sink.
10 Gemmy Facts About Spinel - Is spinel the world*s most overlooked gem?
Pyroxene Minerals are a group of chain silicate minerals found in igneous and metamorphic rocks.
Angel Falls in Venezuela is the tallest waterfall in the world - it is 3212 feet tall.
Solar System Volcanoes - Earth is not the only location of volcanic activity.
Tourmaline - an extremely colorful mineral and gem material.
Charoite is a purple silicate mineral, found only in Russia, used as a gem material.
Phytoplankton Blooms are caused by an explosive growth rate of plankton in surface waters.
California Earthquake Maps - A collection of isoseismal maps for earthquakes in California.
What is a Geyser? Photos and information about geysers in many parts of the world.
Range of Bear Species - Where you might encounter different types of bears.
Deepest Point in the Ocean The deepest point in the ocean is in the Mariana Trench.
Soapstone is a metamorphic rock with properties that make it suitable for a variety of projects.
Mount Etna - The most active volcano in Europe continues an eruption that started in 2001.
What is the San Andreas Fault? Map, photos and description of the fault.
Cinder Cones are the smallest, simplest, and most common type of volcano.
Utica Shale is a major source of oil, natural gas and natural gas liquids in PA, OH and WV.
How Are Hurricanes Named? There is a plan for naming tropical storms.
Storm Surge can be the most damaging and deadly aspect of a hurricane.
Mount Vesuvius - geology, history, maps, facts and more about the Vesuvius eruptions.
NEW Pottery Barn Kids Abigail Design Fitted Crib Sheet With Forg - Small mines in the United States produce a diversity of beautiful gemstones.
Azurite - Used as an ore of copper, a pigment, ornamental stone and gem material.