The Rocky Mountains are home to many kinds of…well, rocks.
This post lets you know about the primary types of rocks you can find in the ARocky Mountains, what they look like, and where you can find them.
Types of Rocks Found In the Rocky Mountains: A Guide
The Rocky Mountains are well known across the world for their beauty and as a geological hotspot in both Canada and the USA.
The range stretches from the northern border of British Columbia down the length of the province and through several states to New Mexico in the USA.
The Rockies, as they are often referred to, are the largest mountain range in North America.
With so much land to cover, it is no wonder that the entirety of the range is a hotspot for fossil, gemstone, and precious mineral hunters.
Much of the range falls under protected park lands and, as such, it is advised to be aware of any and all laws pertaining to collecting samples wherever you go in the Rocky Mountains.
Some of the more common rocks you will be able to find anywhere in the Rocky Mountains include:
By definition, granite is a coarse grained intrusive igneous rock that largely consists of quartz and feldspar material that can be many different colors, all depending on the other trace minerals found within the rock.
The more common colors that can be found are white, black and grey.
Granite is able to withstand even the harshest weather environments on our planet’s surface due to its hardness, making it fairly easy to find and collect.
Identifying what is in a granite sample can be done at a glance, for the most part, by using this rough visual guide:
- Quartz rich granite will have a milky appearance.
- Feldspar rich granite will be more opaque. If it is potassium feldspar, it will look salmon pink.
- Garnet rich granite will have a distinctly red color.
- Silicate rich granite will look green or almost black.
- Mica (muscovite) rich granite will appear golden or yellowish. If the mica is biotite, it will look brown or black.
Finding samples of granite can be done almost anywhere in the Rocky Mountains as it tends to be near the surface and easily visible.
Due to the amount of quartz in granite, it is rather impervious to chemical weathering and can be bare to the elements for a long time without degrading.
You can often find smaller hand sized samples or you can break off a piece from a larger chunk with a rock hammer and chisel.
The most common use for granite these days is on countertops for the kitchen or bathroom due to its beauty.
Granite is also used in building construction to some degree because of how durable it is.
Quartz, like granite, can be found all over the Rocky Mountains and there are many varieties and colors.
Aside from their use in jewelry, as decorative crystals and for their mystical properties in some circles, there are a number of quartz varieties that are sought after as gemstones.
The composition of trace minerals in a piece of quartz will determine its color, but typically it will be white, transparent or a blend of the two.
While quartz can form in crystals, there is much more of it that forms in a rock shape and has large amounts of silica.
Some of the colored quartz that can be found are rose quartz, smoky quartz, white (milky) quartz, and more.
Quartz veins commonly have other gemstones and minerals trapped in them, such as citrine, amethyst, hematite and gold.
Often you can collect quartz samples easily without any tools, but you may want to have a rock hammer and chisel with you in case you find a piece that is attached to a larger rock.
In most cases, though, you can find crystals and quartz rocks freely lying in dirt or on the surface of other rocks.
Agates are a formation of primarily quartz and chalcedony that form inside volcanic material as nodules.
Despite the volcanic nature of their formation process, they are not considered to be igneous rocks.
They also don’t fall into the metamorphic or sedimentary categories either.
It has also been debated as to whether agates are even to be considered minerals, as they fall more specifically under a classification of mineraloids because of their physical and geochemical properties.
Agates are highly sought after for their stunning array of colorful bands, especially when polished. They make beautiful decorative pieces and jewellery.
Agates can be found near any area that has been a volcanic flow bed and finding volcanic material visible on the surface is a clear indicator of a possible agate deposit.
They can typically be hand picked but may need to be broken free of surrounding material with a small rock hammer.
Agates are considered to have various beneficial cognitive properties and are collected for their wide array of colors and their beauty when polished.
They are used in jewellery frequently, and other decorative pieces.
Serpentine is often mistaken for jade due to its similar color, but you can do a simple scratch test to tell it apart as it is softer than jade.
Serpentine has a snakeskin like pattern to its coloration that may need a bit of light to reveal and it has a waxy look and feel to it when you run your finger over its surface.
The softness of the material makes it easy to work with for carvings, sculptures, jewellery and other ornamentation.
Serpentine is a metamorphic rock and is typically found where an oceanic plate has been pushed up and revealed on the surface of the planet.
Other materials found in these exposed layers include jade, chromite, magnetite and more.
There are a number of river and creek banks throughout the Rocky Mountains that have yielded all of these precious materials.
This list barely scratches the surface of the offerings that can be discovered in the Rocky Mountains, but should be a good starting point for any rock hounder.
If you would like to learn more about the various precious gems, minerals and fossils that can be found in the Rockies, check out Garret Romaine’s book: Rocks, Gems, and Minerals of the Rocky Mountains.
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