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Colorado State Rock, Mineral & Gem: Yule marble, Rhodochrosite, Aquamarine

Colorado's state rock is Yule marble, adopted in 2004. Colorado's state mineral is rhodochrosite, adopted in 2002. Colorado's state gemstone is aquamarine, adopted in 1971. Colorado's state fossil is Stegosaurus, adopted in 1982.

Symbol names and dates are taken from primary state sources linked below. Informal or proposed symbols are not listed unless adopted.

Marble specimen
Marble (not necessarily from Colorado). Photo: Zyance, CC BY-SA 2.5, via Wikimedia Commons

State rock: Yule marble

Adopted:
2004
Law:
C.R.S. 24-80-912.7 (HB04-1023)
Variety:
Yule marble

It is a variety of marble. Marble is a metamorphic rock with a Mohs hardness of about 3–4 and a sugary sparkle luster, usually white, gray, pink or green.

How to identify marble →

Often confused with: Anorthosite, Carbonatite, Dolostone

Also an official symbol of: Alabama, Vermont

Rhodochrosite specimen
Rhodochrosite (not necessarily from Colorado). Photo: JJ Harrison (https://www.jjharrison.com.au/), CC BY-SA 4.0, via Wikimedia Commons

State mineral: Rhodochrosite

Adopted:
2002

Rhodochrosite is a mineral (MnCO₃) with a Mohs hardness of 3.5–4 and a vitreous luster, usually pink or red.

How to identify rhodochrosite →

Often confused with: Calcite, Erythrite, Rhodonite

Aquamarine specimen
Aquamarine (not necessarily from Colorado). Photo: Gunnar Ries Amphibol, CC BY-SA 2.5, via Wikimedia Commons

State gemstone: Aquamarine

Adopted:
1971
Law:
C.R.S. 24-80-912

Aquamarine is a mineral with a Mohs hardness of 7.5–8 and a vitreous luster, usually blue or green.

How to identify aquamarine →

Often confused with: Apatite, Euclase, Phosphophyllite

State fossil: Stegosaurus

Adopted:
1982
Law:
Executive order of Governor Richard D. Lamm

Colorado state symbols FAQ

What is the state rock of Colorado?

Colorado's state rock is Yule marble, adopted in 2004 (C.R.S. 24-80-912.7 (HB04-1023)).

What is the state mineral of Colorado?

Colorado's state mineral is rhodochrosite, adopted in 2002.

What is the state gemstone of Colorado?

Colorado's state gemstone is aquamarine, adopted in 1971 (C.R.S. 24-80-912).

What is the state fossil of Colorado?

Colorado's state fossil is Stegosaurus, adopted in 1982 (Executive order of Governor Richard D. Lamm).

Sources

We cite primary sources (statutes, state government pages, federal regulations, and land-manager sites). Third-party listicles are not used as citations.

Last verified 2026-10-24. Corrections welcome: if a statute has changed, tell us and we'll re-verify.

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