Types of Rocks in Argentina: A Guide to the 7 Most Common You’ll Find

Argentina is a wonderful place to hunt for agates of all colors. Jasper, hematite and rhodochrosite are also found in river beds in several locations around Argentina. 

A visit to the San Jose Gemstone Museum can give you an idea of what you may find while exploring Argentina. 

This conveniently located museum is a great place to start your rock hunting trip in Argentina.  

In this article, you’ll learn more about the geology of Argentina.

Types of Rocks in Argentina: A Guide


The information provided in this article by YesDirt.com is for informational purposes and is subject to change. Laws are updated. Accessibility guidelines and restrictions change. Be sure to confirm the land status and collection rules before you travel to an unfamiliar location or collect any material.


Agates are silicate and quartz stones that can be formed in a wide range of colors. 

Agate is a translucent formation of microcrystalline quartz. They are relatively hard and cannot be scratched with a pocket knife. 

Agates form inside volcanic rock and are often cut in half to expose jawbreaker-like layers of colors. 

Volcanic rocks form when lava is extruded and cooled when it comes into contact with air or water. There are different kinds of lava and they contain different amounts of silica. That silica can be extruded into cavities in the rock. 

The colors are often incorporated after the agate is formed inside a volcanic rock and moves to an environment where the porous stone can absorb iron, manganese or other metals that cholor the agate. 

Identify agates by finding very hard translucent stones that have a variety of colors. Agates have a lot of types of formations, you may find single colored gravel sized agates or large multilayer agates. 

Agates may form in many patterns, this article on types of agates can help you get an idea of what type of agate formation you have. 

Agates are closely related to jasper, but are differentiated by the translucence of agates. 

Agates have been used for jewelry, seal stones, and carvings since ancient Greece. 

Where To Find Agates in Argentina

Agates are very popular targets for rock collectors in Argentina. There are three main areas to visit when searching for agates:

 Cuyean Region 

This region contains agates commonly referred to as “condor” agates. Condor agates have brightly colored banding. 

Patagonian Region 

This area is known for Patagonian agates and lots of fossils. There are guided tour options when visiting this area so keep your eye out for agates while visiting the fossil displays. 

Patagonian agates typically have a bright red color and are often found close to jasper. The contrasting red and black make it a striking stone that speaks to it volcanic origins. 

Mesoptiamian Region

This area contains the Entre Rios agates. 

Entre Rios is found on the other side of the Red River that runs through Argentina, the striking bands tend to have white, gray, light brown and beige coloring. 

Be sure to dig down a few inches to see if you turn up any agates. They can be identified by their translucence and hardness. 

While stunning, these stones are very common and the samples found in Argentina have beautiful vivid banding. 


Jasper is a microcrystalline form of quartz that is hard and fine grained. It contains mostly silica and other impurities that make it opaque. 

Jasper is usually red, yellow, brown or green in color and often contains a variety of colors. 

Impressive examples of Jasper have been found in Entre Rios Province in Argentina.  

Jasper has been used since ancient times in ceremonial jewelry in many cultures and for tools like bow drills.   


Hematite is an iron oxide mineral that has a bright metallic luster with a rhombohedral crystal structure.  

It is generally black to gray in color, but can be reddish brown to red if the iron has oxidized. It is found in large quantities in iron banding landscapes. 

Hematite is mined for iron and it is electrically conductive. 


Rhodochrosite is a bright pink translucent rock that can be differentiated from agate by the hardness. 

Rhodochrosite had a hardness of 3-4 on the Mohs scale, so it can be scratched by a steel blade.

The rhodochrosite in Argentina often has white banding and it is found in Capillitas, Argentina. 

The banded forms are more prized for jewelry and the lower quality forms are used in the manufacture of stainless steel.  

The Hill of 7 Colors

Locally known as the Hill of 7 Skirts or Cerro de los Siete Colores in Spanish, the vivid colors of this mountain are the result of many years of sediment. 

The rocks were formed by ocean, river and tectonic movement resulting in 7 distinct colors in the landscape. 

The Seven Colors of the Hill:

  1. Pink – Red clay mixed with sandstone and mudstone
  2. White – Limestone
  3. Brown/Purple – Lead containing 
  4. Brown – Manganese 
  5. Red – Claystone 
  6. Green – Copper oxide
  7. Yellow – Sulfur sandstone 

These rocks vary in age and are thought to have deposited over many millions of years before being thrust to the surface by the movement of the plates. 

Local legend says that the town children escaped from their beds while their parents slept to paint the mountain in vibrant tones. 

It is called the Seven Skirts by many local residents because of its similarity to the colorful skirts worn by local women. 

This landscape is an incredible sight for the rock lover as it is very rare to see this variety of colors so clearly delineated. 

Rainbow Mountain is also a great place to visit and is not overly explored by tourists.


The Patagonia Province in Santa Cruz, Argentina has always been interesting for paleontologists as there have been very large fossils found in the area. 

As recently as 2020 exciting fossils have been found in Argentina. 

While it is illegal to remove fossils, there are many great areas to observe the work being done and see fossils on display in Patagonia. 

Collecting Rocks In Argentina

Argentina is best known for their banded agates and extensive fossil digs. The best way to get close to the fossil operations is to schedule a tour through a tour company. 

Agates in Argentina are often banded and of high enough quality to be used in affordable jewelry, consider supporting the local economy by purchasing some local agate raw or polished into beads.

Types of Rocks in Argentina