The next state up for the Geological State Symbols Across America is:
State Rock: Yule Marble 2004
State Mineral: Rhodochrosite 2002
State Gemstone: Aquamarine 1971
State Fossil: Stegosaurus 1982
I also have two Geology of the National Parks Through Pictures that I have done for Colorado previously. These include:
Black Canyon of the Gunnison National Park
Rocky Mountain National Park
State Rock: Yule Marble
|Tomb of the Unknown Soldier.|
Photo by Thomas Loker Photography (tloker.wordpress.com)
State Mineral: Rhodochrosite
Rhodochrosite is a manganese carbonate mineral (chemical formula (Mn, Fe, Mg, Ca)CO3) with a light pink to bright red color. As you can see with the chemical formula the manganese is frequently replaced with other elements like iron, magnesium, and/or calcium. These substitutions present problems with providing definitive mineral properties since the substitutions cause the specific gravity, hardness, and color of the mineral to vary. Generally though, rhodochrosite has a hardness of 3.5-4 with 3 directions of perfect, rhombohedral cleavage. Rhodochrosite is often found in association with silver mines and is sometimes mined as a by-product in those mines. Rhodochrosite can also be found filling the veins and fractures within metamorphic rocks. In this instance, the minerals are often built up over time with separate mineralization events, each one possibly producing different shades of pink within the mineral. Rhodochrosite can be used as a manganese ore, however there is often not enough of it when found to make it economically viable. Since rhodochrosite is so soft, its use in even jewelry is limited, where it usually ends up being used just as a natural mineralogical sample.
|Rhodochrosite from Sweet Home Mine, Alma, CO|
State Gemstone: Aquamarine
Prospecting for aquamarine began in the late 1800's in the Mt. Antero area of Colorado. Many aquamarine crystals have been found in vugs (holes) within granite pegmatites of the Tertiary Princeton batholith. There are several different types of pegmatites within this region, with two different beryl pegmatites, only one of which contains vugs, or pockets. It is this pegmatite that is the most economically viable for aquamarine specimens. These vuggy beryl pegmatites include not only aquamarine crystals but also crystals of other minerals like microcline, smoky quartz, albite, and fluorite. The veins and pegmatites where the aquamarine has been found are mostly contained within an area roughly 3 miles across; an area that contains the summits of Mt. Antero and White Mt. (as seen in the map to the left). These pegmatites formed at temperatures that ranged from 200°C up to 600°C. Other areas within Colorado that also contain quality aquamarine specimens include Mt. Baldwin and Mt. Princeton, which are both located nearby to White Mt. and Mt. Antero.
State Fossil: Stegosaurus
|Stegosaurus at the Field Museum, Chicago, IL|
Photo by Jim Lehane
Stegosaurus was an herbivore, that lived about 150 million years ago during the Jurassic period. The animal is most well known for the twin row of bony plates that lined its back and a set of spikes on its tail. Scientists are not certain of the use of the plates and several theories have been postulated including defense, display, or even heating/cooling pads (blood vessels ran through the plates allowing the air/sun to heat or cool the plates as needed); however it is pretty universally accepted that the spikes at the end of the tail were for defensive purposes. One of the most commonly known "facts" about Stegosaurus was that it had a very small brain for the size of the animal (it is about the size of a bus, 30 ft in length, with a brain the size of a hot dog). Because of the comparably small size of the brain, scientists at one time thought that Stegosaurus must have had a second "brain", or nerve ball cluster, that operated as a second brain somewhere along the spinal column. This idea came from the discovery of an enlarged canal along the pelvic region, however this theory has since been rejected by scientists. Stegosaurus had a toothless beak, with rounded peg-like teeth further back in its mouth, and a weak jaw, so it likely ate low lying plants like ferns and cycads.