Geology Quick Facts for Each U.S. State

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Listed here are the official state rock, gemstone, mineral, and fossil for each U.S. State. Not all states have an official designation.

What is the difference between a rock and a mineral?

A mineral is an inorganic element or compound with an organized internal structure and distinct chemical composition, crystal shape, and physical qualities that occur naturally. Examples of commons minerals are: quartz, feldspar, mica, amphibole, olivine, and calcite are all common minerals.

A rock is a mineral aggregate or a body of undifferentiated mineral matter made up of one or more minerals. Examples of common rocks are: granite, basalt, limestone, and sandstone.

One source of uranium and radon in the Denver Basin aquifer system is sediments from the Pikes Peak granite, which have been weathering for millions of years.
One source of uranium and radon in the Denver Basin aquifer system is sediments from the Pikes Peak granite, which have been weathering for millions of years. Photo: USGS, public domain.

The most common state rock is granite with five states naming it as their state rock: New Hampshire, North Carolina, South Carolina, Vermont, and Wisconsin.

U.S. Geology Trivia

The first U.S. state to have an official state rock was California in 1965 which is serpentine.

In 2020, 12 mineral commodities produced in the United States were worth more than $1 billion each. In decreasing order of value these 12 mineral commodities are: crushed stone, gold, cement, construction sand and gravel, copper, iron ore, industrial sand and gravel, salt, lime, phosphate rock, zinc, and soda ash.

Alabama

  • State rock: Marble
  • State gemstone: Blue Star Quartz
  • State mineral: Hematite
  • State fossil: Basilosaurus cetoides (Eocene age, whale)

Alaska

  • State gemstone: Jade
  • State mineral: Gold
  • State fossil: Mammuthus primigenius (Pleistocene age, woolly mammoth)

Arizona

  • State gemstone: Turquoise
  • State mineral: Copper
  • State fossil: Araucarioxylon arizonicum (Triassic age, wood)

Arkansas

  • State rock: Bauxite
  • State gemstone: Diamond
  • State mineral: Quartz
  • State fossil: Not Designated

California

  • State rock: Serpentine
  • State gemstone: Benitoite
  • State mineral: Gold
  • State fossil: Smilodon californicus (Pleistocene age, sabertooth cat)

Colorado

  • State rock: Yule Marble
  • State gemstone: Aquamarine
  • State mineral: Gold
  • State fossil: Stegosaurus stenops (Jurassic age, plated dinosaur)

Connecticut

  • State gemstone: Garnet
  • State mineral: No Data
  • State fossil: Eubrontes giganteus (Jurassic age, dinosaur track)

Delaware

  • State gemstone: Silimanite
  • State mineral: No Data
  • State fossil: Belemnitella americana(Cretaceous age, belemnite)

Florida

  • State rock: Agatized coral
  • State gemstone: Moonstone
  • State mineral: No Data
  • State fossil: Not Designated

Georgia

  • State gemstone: Quartz
  • State mineral: Staurolite
  • State fossil: Shark tooth (Cretaceous – Miocene age)

Hawaii

  • State gemstone: Black Coral
  • State mineral: No Data
  • State fossil: Not Designated

Idaho

  • State gemstone: Star garnet
  • State mineral: No Data
  • State fossil: Equus simplicidens (Pliocene age, horse)

Illinois

  • State rock: Salem limestone
  • State gemstone: Fluorite
  • State mineral: No Data
  • State fossil: Tullimonstrum gregarium(Pennsylvanian age, soft-bodied animal – “Tully Monster”)

Indiana

  • State gemstone:No Data
  • State mineral: No Data
  • State fossil: Not Designated

Iowa

  • State rock: Geode
  • State gemstone:No Data
  • State mineral: No Data
  • State fossil: Not Designated

Kansas

  • State rock: Greenhorn limestone
  • State gemstone:No Data
  • State mineral: No Data
  • State fossil: Not Designated

Kentucky

  • State rock: Kentucky agate
  • State gemstone: Freshwater pearl
  • State mineral: Coal
  • State fossil: Brachiopod (Ordovician – Mississippian age, shellfish)

Louisiana

  • State gemstone: Agate
  • State mineral: No Data
  • State fossil: Petrified palm wood (Oligocene age, palm)

Maine

  • State gemstone: Tourmaline
  • State mineral: No Data
  • State fossil: Pertica quadrifaria (Devonian age, plant)

Maryland

  • State gemstone: Agate
  • State mineral: No Data
  • State fossil: Ecphora gardnerae gardnerae(Miocene age, snail); Astrodon johnstoni(Cretaceous age, sauropod dinosaur)

Massachusetts

  • State rock: Roxbury puddingstone
  • State gemstone: Rhodonite
  • State mineral: Babingtonite
  • State fossil: Dinosaur tracks (Jurassic age, trace fossil tracks)

Michigan

  • State rock: Petoskey stone 
  • State gemstone: Chlorastrolite (Isle Royale greenstone)
  • State mineral: No Data
  • State fossil: Mamut americanum (Pliocene – Pleistocene age, mastodon); Petoskey Stone (Devonian age, coral)

Minnesota

  • State gemstone: Agate
  • State mineral: No Data
  • State fossil: Not Designated

Mississippi

  • State rock: Petrified wood 
  • State gemstone: No Data
  • State mineral: No Data
  • State fossil: Basilosaurus (Eocene age, whale); Zygorhiza (Eocene age, whale); petrified wood (Oligocene age, wood)

Missouri

  • State rock: Mozarkite 
  • State gemstone: Galena
  • State mineral: No Data
  • State fossil: Delocrinus missouriensis (Pennsylvanian age, crinoid); Hypsibema missouriense (Cretaceous age, dinosaur)

Montana

  • State gemstone: Sapphire
  • State mineral: No Data
  • State fossil: Maiasaura peeblesorum (Cretaceous age, duckbilled dinosaur)

Nebraska

  • State rock: Prairie agate
  • State gemstone: Blue agate
  • State mineral: No Data
  • State fossil: Archidiskodon imperator (Pleistocene age, mammoth); mammoth (Pleistocene age, mammoth)

Nevada

  • State rock: Sandstone
  • State gemstone: Opal and Tuquoise
  • State mineral: No Data
  • State fossil: Shonisaurus popularis (Triassic age, ichthyosaur)

New Hampshire

  • State rock: Granite
  • State gemstone: Smoky quartz
  • State mineral: Beryl
  • State fossil: Not Designated

New Jersey

  • State gemstone: No Data
  • State mineral: No Data
  • State fossil: Hadrosaurus foulkii (Cretaceous age, duckbilled dinosaur)

New Mexico

  • State gemstone: Turquoise
  • State mineral: No Data
  • State fossil: Coelophysis bauri (Triassic age, theropod dinosaur)

New York

  • State gemstone: Garnet
  • State mineral: No Data
  • State fossil: Eurypterus remipes (Silurian age, sea scorpion)

North Carolina

  • State rock: Granite
  • State gemstone: Emerald
  • State mineral: Gold
  • State fossil: Not Designated

North Dakota

  • State gemstone: No Data
  • State mineral: No Data
  • State fossil: Teredo petrified wood (Paleocene age, shipworm-bored wood)

Ohio

  • State gemstone: Flint
  • State mineral: No Data
  • State fossil: Isotelus (Ordovician age, trilobite)

Oklahoma

  • State rock: Rose rock (Barite)
  • State gemstone: No Data
  • State mineral: No Data
  • State fossil: Saurophaganax maximus (Jurassic age, theropod dinosaur)

Oregon

  • State rock: Thunderegg agate 
  • State gemstone: Oregon sunstone
  • State mineral: Oregonite and Josephinite
  • State fossil: Metasequoia (Miocene age, conifer leaf)

Pennsylvania

  • State gemstone: No Data
  • State mineral: No Data
  • State fossil: Phacops rana (Devonian age, trilobite)

Rhode Island

  • State rock: Cumberlandite 
  • State gemstone: Bowenite
  • State mineral: No Data
  • State fossil: Not Designated

South Carolina

  • State rock: Blue granite 
  • State gemstone: Amethyst
  • State mineral: No Data
  • State fossil: Not Designated

South Dakota

  • State rock: none
  • State gemstone: Agate
  • State mineral: Rose quartz
  • State fossil: Triceratops (Cretaceous age, horned dinosaur)

Tennessee

  • State Rock: Limestone
  • State gemstone: Tennessee River Pearl 
  • State mineral: Agate
  • State fossil: Pterotrigonia thoracica(Cretaceous age, bivalve)

Texas

  • State rock: Oligocene petrified palmwood 
  • State gemstone: Texas blue topaz
  • State mineral: Silver
  • State fossil: Pleurocoelus (Cretaceous age, sauropod dinosaur); petrified palm wood (Oligocene age)

Utah

  • State rock: Coal
  • State gemstone: Topaz
  • State mineral: Copper
  • State fossil: Allosaurus (Jurassic age, theropod dinosaur)

Vermont

  • State rock: Granite, marble, and slate
  • State gemstone: Garnet
  • State mineral: Talc
  • State fossil: Delphinapterus leucas (Pleistocene age, white beluga whale)

Granite is an igneous rock. Granite’s name originates from the Latin word “granum,” which means “grain,” and alludes to the quartz and feldspar grains that make up the rock.

Photo of barre granite in Vermont.
Barre Granite: from the Barre formation in Vermont. Photo: USGS, public domain.

Virginia

  • State rock: Nelsonite
  • State gemstone: No Data
  • State mineral: No Data
  • State fossil: Chesapecten jeffersonius (Miocene – Pliocene age, bivalve)

Washington

  • State rock: None
  • State gemstone: No Data
  • State mineral: Petrified wood
  • State fossil: Not Designated

West Virginia

  • State rock: Bituminous coal
  • State gemstone: No Data
  • State mineral: Fossil coral (Lithostrotionella)
  • State fossil: Not Designated

Wisconsin

  • State rock: Red granite
  • State gemstone: No Data
  • State mineral: Galena
  • State fossil: Calymene celebra (Ordovician – Silurian age, trilobite)

Wyoming

  • State rock: None
  • State gemstone: Jade
  • State mineral: No Data
  • State fossil: Knightia (Eocene age, fish); Triceratops (Cretaceous age, horned dinosaur)

References

Unofficial national register of Geoheritage sites. (2020, December 28). NPS.gov (U.S. National Park Service). https://www.nps.gov/subjects/geology/unofficial-register.htm

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