Turquoise is a semi-precious stone derived from the earth. It is a hydrous phosphate of copper and aluminum, usually with a blue to greenish-blue color. The name turquoise comes from the French word ‘Turquie,’ which means “Turkish stone” due to its popularity in Turkey during the Ottoman Empire.
The formation of turquoise starts deep within the Earth’s crust, where underground pools of hydrothermal fluid suspend minerals. As this fluid mixes with limestone or sandstone deposits, it builds up copper and aluminum oxide concentrations.
These elements begin to crystallize around other elements like phosphorus, silica, and manganese. When all these elements combine, they form a hydrous phosphate that gives turquoise its signature blue-green hue.
You’ll often see darker lines or blotches of color embedded into turquoise stones. This is what is referred to as the matrix. The matrix comes from the mother or hosting rock, which is limestone or sandstone.
Limestone produces dark brown markings, while sandstone usually produces lighter tan colored markings.
One of the reasons why turquoise has become a rare commodity is because it can only form in specialized environments. First, turquoise only forms in dry, arid climates. That’s why the turquoise mines existing in the US are in our desert regions.
As mentioned before, turquoise must also form within a sandstone or limestone hosting rock and be exposed to other specific elements to create this semi-precious stone. Very few regions in the world provide the minerals and climate necessary for turquoise to form, making it a rare stone.
Turquoise is mined in various ways, with the most common method being open-pit mining. This involves digging deep trenches and using pickaxes to break up the rock containing the turquoise. The material is then sifted through screens to remove any dirt or rock that doesn’t contain turquoise.
Another factor making natural turquoise more valuable is that many US mines have become depleted over the decades.
For example, the Cerillos mine in New Mexico opened during the 1800s and provided an abundant source of turquoise for the Navajo people in the Southwest region. Through the turquoise booms and periods of low demand, this mine eventually depleted and no longer produces turquoise today.
Cerillos is no exception, though. Many US mines have become depleted, making natural turquoise harder to find and more valuable than ever.
As mines depleted, stabilizing turquoise became a necessity. Stabilized turquoise is turquoise that has undergone treatment to make the generally soft stone harder and more stable for jewelry making.
Between the depletion of mines and the large amounts of stabilized turquoise hitting the markets, natural turquoise is now rarer and more valuable than ever, which is why buying your Navajo jewelry from a reputable seller is crucial. They’ll have the expertise to authenticate turquoise, letting you know exactly what you’re buying.