Lead makes amazonite green. Experts aren’t sure why or how small quantities of lead turn amazonite green, but many think the lead interacts with light, absorbing some wavelengths and reflecting the colors green and blue-green.
But there’s a fascinating story behind this tale. Let’s dive deeper into how amazonite forms and becomes green, and what those white streaks are in some amazonite crystals.
In this blog post, you’ll discover:
- How amazonite forms
- What makes up amazonite and why it’s green
- What those white streaks are in amazonite crystals
How Amazonite Forms
Let’s start at the beginning to find out where amazonite comes from.
Amazonite starts off as hot liquid rock
It all starts deep within the Earth, where there is a layer called the mantle. Inside the mantle, there’s an extremely hot liquid called magma.
Magma contains all the minerals and elements needed to make rocks and other natural materials, like amazonite crystals.
But these minerals and elements are all mixed together and move around in the magma.
I like to call magma “hot rock soup” because it’s extremely hot liquid with lots of ingredients, and it steams and sprays whenever it gets a gap…
This liquid rock finds a way onto Earth’s surface
The ground you walk on every day is part of the Earth’s crust, and it’s made of solid rock.
Liquid magma in the mantle puts a lot of pressure on the Earth’s crust, and it’s always looking for a way out.
When this pressure gets too strong or something happens to make the rocks on the crust move or separate, an opening is created for the hot magma to escape.
Magma now has a chance to come up to Earth’s surface through a volcano or other opening, and it either flows like a river of fire or explodes up into the air.
Magma is now called lava because it’s on the Earth’s surface.
The liquid rock starts cooling down
But the Earth’s surface is nowhere near as hot as the Earth’s mantle (thank goodness or we’d all be soup).
It’s time for our runny hot rock soup to turn into thick, cold soup!
Lava quickly cools down when it comes into contact with the cooler air or water on Earth.
Cooled lava now turns to rock
When cooled, lava turns into rocks that contain minerals and elements from the magma.
Cooling and hardening into rock can take several hours or a few days on the Earth’s surface. But this process can take weeks or even millions of years if it happens under the Earth’s surface.
When magma cools down nice and slowly underground like this, it leaves enough time for amazonite crystals to grow inside the rocks.
This happens only if the right minerals and conditions are available to grow amazonite.
What makes amazonite and turns it green
Now we know how amazonite forms, let’s take a look at what elements need to come from the magma to grow green amazonite crystals inside lava rocks.
Amazonite is a type of microcline feldspar. Feldspars are minerals that form rocks and they make up a big portion of the Earth’s crust.
If amazonite is a microcline feldspar, then it makes sense that it must have all the elements of a microcline feldspar in it.
Microcline feldspar is made up of potassium, aluminum, silicon, and oxygen, and so is amazonite.
But microcline feldspar comes in different colors, depending on what trace elements are in the crystal and the conditions under which it formed.
Each color has a different name. For example, orange microcline feldspar is known as adularia.
When lead is present in trace amounts, microcline feldspar turns green or blue-green. This green microcline feldspar is called amazonite.
Why there are white markings in amazonite
You might see or own an amazonite crystal with white flecks or streaks in it.
The white markings in amazonite are a different feldspar mineral, called albite.
Amazonite with white albite in it is still a genuine amazonite crystal, but it’s usually worth less than amazonite without albite in it. Here’s how to tell if a crystal is real amazonite or not, with pictures.
Amazonite gets white streaks or flecks in it through a process called exsolution.
In exsolution, one solid mineral divides into at least two different minerals during its cooling and solidification phases. No minerals or elements are added or taken away during this process.
In the case of amazonite, the growing crystal separates into green amazonite and white albite during exsolution.
It’s almost like some elements want to become amazonite and some want to become albite, so the two different minerals form separately in layers but within the same crystal.