Types of Rocks Found In Uruguay: A Guide To the 7 Most Common You’ll Spot 

Uruguay is an incredible place to find stunning geodes, agates and granites. Volcanic rocks like basalt, granite and andesite are mostly found in the northwest. There is no mining tradition in Uruguay so the arrival of commercial mining is recent. 

Uruguay is now a global exporter of large slabs of multicolored granites.

Mining in northern Uruguay unearths incredible amethyst and geodes. Famously a heart shaped geode was unearthed in Artigas, Uruguay. 

Uruguay is known for its gemstones and granites. 

Types of Rocks Found In Uruguay

Disclaimer

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.

Amethyst

Amethyst is the name for purple varieties of quartz and the amethyst found in Uruguay is of the highest quality. 

Much of the mining of amethyst takes place in a mine in Artigas in northern Uruguay. 

The deep violet color of the stones found here is what makes them so valuable and unique. 

Their color comes from iron in the quartz and sometimes other metals. 

Amethyst is a type of quartz, so it is a glassy transparent stone that has a hardness of 7. It is easy to identify because of its striking color. 

Collectors can find an abundance of gem quality amethyst jewelry for sale in Uruguay. It is also possible to purchase raw stones in many areas. 

The largest geode of amethyst ever discovered was found in Uruguay and is on display at the Australian museum called Crystal Caves. 


The geode called The Empress of Uruguay is almost 11 feet tall and weighs over 2.5 tons. At one time it was possible to purchase pieces of the geode in the museum gift shop. 

The stone is easy to care for in jewelry and has been used since ancient times for jewelry and other decorative purposes. 

It is believed that the wearer of amethyst will be protected from drunkenness. 

Granite

Granite is a major mining export of Uruguay and it is well known for its bright coloration.

Granite is a volcanic rock that consists of coarse grains that are visible when polished. It is composed of quartz, feldspar, and alkali.

The stone has been used for architecture and decoratively since ancient times. The trends in construction change frequently over time affecting the types and amount of granite mined. 

Raw granite pieces can be identified by the visible different colored grains incorporated into the stone. 

While large pieces of granite are mined and exported, many smaller pieces are used for gravel or other industrial applications. 

The granite in Uruguay is very diverse in color.  This image of samples of polished granite mined in Uruguay show the wide variety of granites mined. 

There are three color classifications of granite that are found in Uruguay. 

Black Granite

Black granite is a common name for dolerite and gabbro-norites, these volcanic stones form when lava cools and solidifies. 

This color is highly sought after and considered to have a classic look and appeal. 

Black granite stones are less common than some other varieties making it more desirable. 

Red Granite

Red granite is a common felsic type of granite that has a red hue. It is less popular in decore than some other colors of granite. 

Red granite is often heavily veined with browns or blacks. 

Gray Granite

Gray granite is often used for more practical than decorative purposes. Granite is used for countertops, buildings, gravestones and curling stones. 

You may see all colors of these stones being used for these purposes, but the majority of the gray granite you see is in rugged construction or gravestones. 

Basalt

Basalt is a volcanic rock that is formed when molten rock is pushed to the surface and cools quickly when exposed to air or water. 

Basalt is the most common type of volcanic rock found on the surface of the Earth. 

The stone can be identified by its very dark to black color and its dense texture. 

The rock is common in Uruguay although it has mostly been covered by sedimentary rock. The exposed basalt is mostly seen in northwest Uruguay. 

Andesite

Andesite is another common volcanic rock found in Uruguay. 

Andesite differs from basalt by being lighter in color and containing more silica than andesite. 

Andesite is formed when a higher silica containing lava is pushed to the surface of the Earth and solidifies. This is called extrusive rock. 

Andesite is generally gray in color but it can be brown in some cases. The stone is very dense and smooth when polished but has a dull or earthy luster. 

Sandstone

Sandstone is found all over Uruguay as it formed over the volcanic rock foundation of the country. 

Sandstone is a sedimentary rock that is formed when individual grains of sand cement together, usually at the bottom of the ocean. 

It is often possible to see the individual grains of sand in a piece of sandstone with your naked eye. 

Most often sandstone is yellow, brown or tan, but it can take on any color if it contains other impurities. 

It is a porous stone and may bubble when placed in a cup of water. 

Some areas of the country do not contain sandstone as it has eroded away over time. 

Geodes

Geodes are highly collectable and some incredible geodes have been found in Uruguay. 

Geodes are found here in the large flood basalts in the northern part of the country. 

The geodes found in Uruguay are most commonly amethyst geodes that are carefully extracted from basalt. 

Geodes are collections of minerals that form inside empty spaces in volcanic rock. 

They are stunning and Uruguay is finding some of the largest in the world. 

In 2007 The Empress of Uruguay was found, an 11 foot tall amethyst geode, and in 2021 a 22 foot one was unearthed. 

Geodes can be difficult to identify, but you can find some tips online for identifying these hidden treasures. 

Rocks in Uruguay

Volcanic rocks are generally boring to collectors because they are so geologically young, but in Uruguay there are incredible amethyst geodes hiding in all that basalt. 

Be sure to collect rocks only where permitted and obey any local laws and posted restrictions when hunting for these treasures. 

Types of Rocks Found In Uruguay