Nevada

 

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Nevada State Geological Symbols
Type
Symbol
Year Est.
State Rock
Sandstone
1987
State Precious Gemstone
Virgin Valley Black Fire Opal
1987
State Semi-Precious Gemstone
Nevada Turquoise
1987
State Fossil
Ichthyosaur
1977
State Metal
Silver
1977

 

State Rock: Sandstone

 

 

State Precious Gemstone: Virgin Valley Black Fire Opal

The chemical composition of opal is a hydrous silicon dioxide (SiO2.nH2O). Silica, SiO2, is more commonly known as quartz, and is one of the most common minerals on the planet. Opal then could be considered the hydrated form of quartz, however the water ends up making the properties of opal very different from quartz. Although quartz itself can come in a variety of colors (i.e. white, pink, purple, grey, clear), the colors within a crystal of quartz are usually pretty consistent. Opal on the other hand can often come in a wide range of colors, anything in the rainbow and beyond really, all within a single sample. And while quartz is often found in crystals, opal is amorphous, meaning it has no crystal structure. Also, since opal can have varying amounts of water (the "n" in the chemical formula), this actually makes is a mineraloid, and not a true mineral (minerals have a set chemical formula). Another primary property of opal is that it has a hardness on the Mohs Hardness Scale of 5.5 to 6, making it much softer than most gemstones (quartz is a 7). Opal forms from the seasonal rains that drench dry grounds in desert regions. The rain soaks into the ground surface, carrying with it dissolved silica. After the water evaporates, the water imbued silica is left behind, forming opal. There are two types of opal, common and precious. Common opal doesn't have a wide array of fantastical colors and typically can be confused for quartz or chalcedony. The precious type of opal is very different though, with a wide array of colors within a single specimen. Due to the formation of opal, it is often formed as sub-microscopic spheres that are stacked in a grid-like pattern. These spheres bend the light creating the array of colors, known as "play-of-color". The size of the spheres directly relates to the colors that you can see. 

 

There are many different types of opal depending on the play-of-color that you can see. 

 


State Semi-Precious Gemstone: Nevada Turquoise

Turquoise is a blue-green mineral made up of copper, aluminum, and hydrous phosphate (CuAl6(PO4)4(OH)). The name turquoise comes from the French expression for "Turkish Stone", illustrating that the early sources for European turquoise were from the Middle East. Turquoise has long been considered valuable and is one of the oldest known gemstones. It has been found in ancient Egyptian and Chinese archeological expeditions, showing that those people used turquoise as far back as 3,000 years ago. It is formed by the flowing of groundwater through copper deposits that eventually react with phosphate and aluminum minerals. Turquoise is also only found in arid (desert) environments because that is one of the few places that allows the groundwater to maintain a high enough copper concentration for long enough to interact with the other minerals. The result is a gemstone unlike traditional, gemstones like ruby or emerald, which is most commonly opaque. The opaqueness is due to the structure of turquoise, which is made up of many microcrystalline structures instead of one large mineral crystal. These microcrystals give the turquoise its appearance, either a mottled look or a smooth finish, which is due to the size of these microcrystals. It is also extremely soft and easy to carve. All of these attributes make it useful for many different purposes from jewelry to architectural adornments.

 

Related: Arizona State Gemstone - Turquoise; New Mexico State Gem - Turquoise


State Fossil: Ichthyosaur

 

 

State Metal: Silver


 

References

https://statesymbolsusa.org/states/united-states/nevada


Geology of Nevada's National Parks

Through Pictures

(at least the one's I have been to)

Death Valley National Park


Death Valley National Park

Visited in 2016

Death Valley National Park

For all of the pictures from Death Valley National Park be sure to head over to the:

California Page