Crystal Habit is the external shape displayed by a crystal or an aggregate of crystals.
What Is Luster? Luster is the light-reflecting characteristics of a mineral specimen.
Sand is a diverse material. This gallery includes photos of sand from around the world.
Mohs Hardness Scale is a set of reference minerals used for classroom hardness testing.
Hardness Picks - Test for hardness with precise and easy-to-use hardness picks.
Coquina - A porous limestone composed almost entirely of fossil debris.
Mount Etna - The most active volcano in Europe continues an eruption that started in 2001.
Largest Hurricanes Are they determined by wind speed, value of damage, most deaths?
Volcanic Explosivity - Rating volcanic eruptions based upon the volume of tephra ejected.
The Acid Test - Geologists use dilute hydrochloric acid to identify carbonate minerals.
World Record Lightning - this lake has more lightning than any other place in the world.
Blue Flames and the largest highly acidic lake in the world at Kawah Ijen Volcano.
Ruby and Sapphire are the 2nd and 3rd most popular colored stones in the United States.
Teacher Resources - K-12 resources for teaching about earth science.
Tallest Tsunami - A wave with a run-up height of 1720 feet occurred in Lituya Bay, Alaska.
Largest Earthquake ever recorded - Magnitude 9.5. Chile, 1960.
Solar System Volcanoes - Earth is not the only location of volcanic activity.
Rock Tumblers - All about rock tumblers and rock tumbling. Read before you buy a tumbler.
Utica Shale is a major source of oil, natural gas and natural gas liquids in PA, OH and WV.
Rock & Mineral Kits The best way to learn about rocks and minerals is with specimens!
Mars Meteorites Mars rovers have found dozens of meteorites while exploring the red planet.
Types of Maps - Explore some of the most popular types of maps that have been made.
What is the San Andreas Fault? Map, photos and description of the fault.
Cinnabar - the only important ore of mercury. Used in pigments until its toxicity was realized.
Rocks - Galleries of igneous, sedimentary and metamorphic rock photos with descriptions.
Morganite is an orange to pink gemstone, a variety of beryl, that is growing rapidly in popularity.
US Diamond Mines - Did you know that diamonds have been mined in the United States?
Pictures of Opal - A collection of different types of opal from all around the world and Mars too!
Fool*s Gold is a name used for pyrite when its brassy color fools people looking for gold.
Ticks are a problem for geologists in some areas. Learn to recognize and avoid them.
California Earthquake Maps - A collection of isoseismal maps for earthquakes in California.
Geology Tools Rock hammers, field bags, hand lenses, maps, hardness picks, gold pans.
Mineraloids are amorphous naturally-occurring inorganic solids that lack crystallinity.
Mined in America - Small mines in the United States produce a diversity of beautiful gemstones.
Hawaii*s Next Island could be growing in the Pacific Ocean right now. Its name is Lo*ihi.
Charoite is a purple silicate mineral, found only in Russia, used as a gem material.
The Science of Fireworks Learn how the colors and shapes are created.
Deepest Point in the Ocean The deepest point in the ocean is in the Mariana Trench.
Rhodochrosite - a manganese mineral used as an ore, a pink gem and an ornamental stone.
Obsidian - the volcanic rock that cools so quickly that it becomes a natural glass.
The Many Uses of Gold - Unique properties make gold one of the most useful metals.
Soapstone is a metamorphic rock with properties that make it suitable for a variety of projects.
Free Google Earth software allows you to browse seamless world satellite images. Free.
Methane Hydrate deposits contain more fuel value than all other fossil fuels combined.
Minerals - Descriptions, photos, articles, properties and uses for common minerals.
Corundum is the third hardest mineral. It is also the mineral of ruby and sapphire.
Range of Bear Species - Where you might encounter different types of bears.
Colored Diamonds are diamonds with a noticeable body color. They can sell for over $1M/carat.
Labradorite is a feldspar mineral that sometimes exhibits an iridescent play-of-color.
Copper Kills COVID-19 and many other pathogens to limit the spread of disease.
How Are Hurricanes Named? There is a plan for naming tropical storms.
Novarupta - The most powerful volcanic eruption of the 20th century occurred in the U.S.A.
Birthstones are gems assigned to the month of a person*s birth. They are popular gifts in the U.S.
Wall Maps - Wall maps of the world, continents, states and the USA.
Azurite - Used as an ore of copper, a pigment, ornamental stone and gem material.
The Rock Used to Make Beer - Geologists are beer experts and should know about this rock.
Geodes look like ordinary rocks on the outside but can be spectacular inside!
Shale - The rock that has quickly transformed the oil and gas industry.
Diamond Misconception - Many people think that diamonds form from coal. Not True!
Faurn Girls Mary Jane Low Heel Glitter Flat Bowknot Princess Par - The intrusive igneous rock that underlies continents and countertops.
What Is Earth Science? The study of Earth and its neighbors in space. Learn more!
What is Geology? The study of Earth materials, structures, processes and life over time.
Geology Books - A variety of books for reference, field trips, reading and more.
The East Africa Rift System - The extensive fault system that is tearing Africa apart.
Expansive Soil causes more damage than floods, hurricanes & tornadoes combined.
YueZiming Bread Basket for Restaurant Rattan Basket 3Pcs Tableto - The new opal heavyweight that might give Australia a run.
Portable UV Lamp - Short and long wave UV for fluorescent mineral viewing.
Rock Art - People have been marking on rocks for thousands of years.
Plate Tectonics - Articles and maps about plate tectonics and the interior of Earth.
What Is The Moho? The Mohorovicic Discontinuity is the mantle/crust boundary.
Gemstones - Colorful images and articles about diamonds and colored stones.
Bear Attacks - Knowing how to react to a bear encounter or attack could save your life.
Lapis Lazuli - a metamorphic rock and the most popular blue opaque gemstone in history.
Petrified Wood is a fossil that forms when silica replaces and infills the cavities of wood.
Quartzite is metamorphic rock formed when sandstone is subjected to heat and pressure.
Sliding Rocks Mystery - What causes these rocks to slide across a playa in Death Valley?
Hand Lens A 10-power folding magnifier in a metal case. A frequently used lab and field tool.
Rare Earths - Special materials used in electronics, defense, medical & many other products.
Ant Hill Garnets - tiny gems that ants haul to the surface and discard on their anthill. Honest!
Diamonds - Learn about the properties of diamond, its many uses, and diamond discoveries.
Crater of Diamonds - The only diamond mine in the world where you can be the miner.
Grape Agate is a popular mineral specimen with the color and the shape of a bunch of grapes.
Cave of the Hands is a cave where ancient people painted hands about 9000 years ago.
Emerald is the most popular green gemstone in the United States and most of the world.
Gold Pans and Panning Kits - classifiers, snuffer bottles. Learn how to pan for Gold.
Waterproof Paper - Don't take chances with your field notes and maps. Use waterproof paper.
Tallest Mountain - Everest has rivals in tallness, altitude and distance to the center of Earth.
What is a Geyser? Photos and information about geysers in many parts of the world.
Rhyolite An extrusive igneous rock with a high silica content, produced from granitic magma.
Hematite - The most important ore of iron. A source of mineral pigment since prehistory.
World*s Largest Diamonds Records for the largest rough, faceted and carbonado diamond.
Turquoise - A bluish-green gem material that has been used for over 6000 years.
Lightning Strikes Map by NASA shows the worldwide distribution of lightning activity.
Rock Salt is a sedimentary rock composed of the mineral halite. It has many uses!
Mineral Rights - Who owns the minerals under your land? Who wants to buy them?
Peridotite is a chromite host rock, a source of diamonds and a possible carbon dioxide sink.
Tourmaline - an extremely colorful mineral and gem material.
Field Courses - Over 80 field courses for undergraduate geology students.
Tanzanite was unknown until a few decades ago but it has erupted into wide popularity.
Chocolate Covered Oreo Cookies - Articles about volcanoes, volcanic hazards and eruptions past and present.
What is a Maar? The second most common volcanic landscape feature on Earth.
Meteorites - Rocks that were once parts of planets or large asteroids.
Gifts That Rock - What are the most popular gift items in the Geology.com store?
Fluorescent Minerals and rocks glow with spectacular colors under ultraviolet light.
Gem Silica is a blue chalcedony colored by copper. It is the rarest and most valuable chalcedony.
100+ Gems - Photos of over 100 beautiful gems ranging from the popular to the obscure.
Cinder Cones are the smallest, simplest, and most common type of volcano.
Know the Rules before removing rocks, fossils or minerals from public or private property.
Ilmenite - The primary ore of titanium and source of most titanium dioxide.
Angel Falls in Venezuela is the tallest waterfall in the world - it is 3212 feet tall.
Fire Opal is a transparent to translucent opal with a yellow, orange or red background color.
Rocks on Mars Many of the rocks found on Mars are not very different from Earth rocks.
Citrine is the transparent variety of quartz with a yellow to orange to reddish color.
10 Gemmy Facts About Spinel - Is spinel the world*s most overlooked gem?
Olivine - Abundant in Earth*s mantle. A constituent of meteorites. The gem peridot.
Herkimer Diamonds Doubly-terminated quartz crystals used as specimens and gems.
Names Used for Great Britain, British Isles, United Kingdom, and Ireland. What they mean.
Debris Flows are moving masses of loose mud, sand, soil, rock and water.
Topo Maps - The DeLorme Atlas is an entire state of topo maps in one convenient book.
Talc is a soft mineral used in cosmetics, paper, paint, ceramics and many other products.
Horizontal Drilling has opened new resources and significantly improved productivity.
The Unsung Mineral Hero - and the commodity upon which almost everything is built.
How did the Hawaiian Islands Form? The power of a moving plate over a stationary hot spot.
Coal Through a Microscope - Coal is more than a black rock. It is THE most interesting rock.
Chalk is a variety of limestone formed from fine-grained marine sediment known as ooze.
Extraterrestrial Gems - A number of materials from space are used as attractive gems.
Mount Vesuvius - geology, history, maps, facts and more about the Vesuvius eruptions.
Homeowners Insurance might not cover earthquake, hurricane and other geohazard damage.
Largest Volcano - That title is shared by Tamu Massif, Mauna Kea and Ojos del Salado.
Zircon is the primary ore of zirconium and a gemstone that is available in many colors.
Storm Surge can be the most damaging and deadly aspect of a hurricane.
The Uses of Marble are numerous and diverse. You will be surprised by how it is used.
Types of Volcanic Eruptions - A description of the most common eruption types.
Chalcopyrite - The most important ore of copper for over five thousand years.
Pyroxene Minerals are a group of chain silicate minerals found in igneous and metamorphic rocks.