Geology

Can you identify my rock or mineral?

Rocks and minerals are extremely difficult to identify through photographs. You will get the best results by taking your rock or mineral to a local source where it can be handled and examined closely. Possibilities include:

Your state geological survey
A natural science museum
A college or university with a geology department
A rockshop
Members of a local Gem & Mineral club or Rockhunting club (many hobbyists are experts at identification)
Vendors at a Gem & Mineral show

Geology professionals and hobbyists love to identify rocks!

Related Content

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Examining sediment core

Can the USGS do a survey or study of my private property?

No. The USGS Organic Act (43 U.S. Code § 31) prohibits the USGS from making surveys or examinations for private parties or corporations. On rare occasion, however, the USGS might request access to private property as part of a larger study. If you need to engage a professional land surveyor, hydrologist, geologist, or geotechnical engineer, the...

Juneau Icefield

Is glacier ice a type of rock?

Glacier ice, like limestone (for example), is a type of rock. Glacier ice is actually a mono-mineralic rock (a rock made of only one mineral, like limestone which is composed of the mineral calcite). The mineral ice is the crystalline form of water (H 2 O). It forms through the metamorphism of tens of thousands of individual snowflakes into...

Image: Sandstone Detail

What are sedimentary rocks?

Sedimentary rocks are formed from pre-existing rocks or pieces of once-living organisms. They form from deposits that accumulate on the Earth's surface. Sedimentary rocks often have distinctive layering or bedding. Many of the picturesque views of the desert southwest show mesas and arches made of layered sedimentary rock. Common Sedimentary Rocks...

Aerial photograph showing a large, deep, circular depression with an elevated rim in the barren desert

How can I tell if I have found an impact crater?

There are many natural processes other than impacts that can create circular features and depressions on the surface of the Earth. Examples include glaciation, volcanism, sinkholes, atolls, salt domes, intrusions, and hydrothermal explosions (to name just a few). Prehistoric mines and quarries are also sometimes mistaken for impact craters...

Image: Celestite

What is the difference between a rock and a mineral?

A mineral is a naturally occurring inorganic element or compound having an orderly internal structure and characteristic chemical composition, crystal form, and physical properties. Common minerals include quartz, feldspar, mica, amphibole, olivine, and calcite. A rock is an aggregate of one or more minerals, or a body of undifferentiated mineral...

Image: Pahoehoe Crack

What are igneous rocks?

Igneous rocks (from the Latin word for fire) form when hot, molten rock crystallizes and solidifies. The melt originates deep within the Earth near active plate boundaries or hot spots, then rises toward the surface. Igneous rocks are divided into two groups, intrusive or extrusive, depending upon where the molten rock solidifies. Intrusive...

Close up of Garnet Schist

What are metamorphic rocks?

Metamorphic rocks started out as some other type of rock, but have been substantially changed from their original igneous , sedimentary , or earlier metamorphic form. Metamorphic rocks form when rocks are subjected to high heat, high pressure, hot mineral-rich fluids or, more commonly, some combination of these factors. Conditions like these are...

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Close up of Fluorite

Date published: April 4, 2017

EarthWord–Rock vs. Mineral

Ever wondered what the difference between a rock and a mineral was? This EarthWord should cover it...

Attribution: Energy and Minerals, Mineral Resources Program

Filter Total Items: 9

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Geologist collects multiple samples of rocks exposed in a glacial stream valley near Lake Clark

July 17, 2017

Geologist collecting rock samples exposed in a glacial stream valley

USGS research geologist Jamey Jones collects multiple samples of rocks exposed in a glacial stream valley near Lake Clark.

Attribution: Region 11: Alaska, Alaska Science Center

scientists in field looking at rocks

December 31, 2016

Scientists Examine Rocks in the Jicarilla Mountains, NM

USGS geologists and collaborator from New Mexico Bureau of Geology and Mineral Resources examine rocks in the Jicarilla Mountains, New Mexico.

Attribution: Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center

A picture of an USGS scientist evaluating rock samples from Cuyama Valley

September 30, 2016

USGS scientist evaluating rock samples from Cuyama Valley

Randy Hanson evaluates rock samples from Cuyama Valley. Studying area geologic formations and history informs scientists about how water may flow through an aquifer, and how water quality might be affected by rocks and sediments in the groundwater system.

Attribution: California Water Science Center

Image: Scientists Collect Data on Yosemite Rock Erosion

March 15, 2016

Scientists Collect Data on Yosemite Rock Erosion

Yosemite National Park geologist Greg Stock and USGS civil engineer Brian Collins download data from instruments measuring how much granitic exfoliation sheets move from daily temperature variations as a precursor to rock fall.

Geologist examines granitic rocks in outcrop before collecting samples for geochemistry and geochronology

July 20, 2015

Geologist checks a granitic rock before geochemistry and geochronology

USGS geologist Erin Todd examines granitic rocks in outcrop before collecting samples for geochemistry and geochronology in Lake Clark National Park, Alaska.

Attribution: Region 11: Alaska, Alaska Science Center

Geologist examining a rock from a pyroclastic flow deposit, Mount H...

September 21, 2007

Examining a rock from a pyroclastic flow deposit, Mount Hood, OR

Above the geologist's head, a second pyroclastic-flow deposit can be seen where there is a horizontal contact (line) between the two deposits. These flows were emplaced during the Timberline eruptive period, which occurred about 1,500 years ago, and helped to build the broad fan of pyroclastic-flow and lahar deposits that forms the southwest flank of the volcano.

Attribution: Natural Hazards, Volcano Hazards Program Office, Mount Hood

USGS scientists examine new rock samples from the new growth on Mou...

November 4, 2004

USGS examine new rock samples from new growth on Mount St. Helens

USGS scientists examine new rock samples from the new growth on Mount St. Helens' dome.

Attribution: Natural Hazards, Volcano Hazards Program Office, Region 9: Columbia-Pacific Northwest, Cascades Volcano Observatory, Mount St. Helens

Obsidian rock from Obsidian Cliff, Yellowstone National Park....

May 20, 2001

Obsidian rock from Obsidian Cliff, YNP.

Close view of rocks from from Obsidian Cliff. This outcrop exposes the interior of a thick rhyolite lava flow erupted about 180,000 years ago.

Attribution: Natural Hazards, Volcano Hazards Program Office, Yellowstone

Picture of camp participant identifying rock types

GeoCamp, rock identification

Hands-on experience identifying rock types while rafting along the Cheat River.

Attribution: Core Science Systems, National Geological and Geophysical Data Preservation Program