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Posted by administrator on October 6th, 2015

Amethyst: Where does it come from?

Amethyst Close Up

When underground magma cools, it usually turns into a common igneous rock called basalt. Air bubbles trapped within the cooled rock are called vesicles, and over time, water that is laden with dissolved silica and other minerals seep through, filling these air pockets. The minerals are left behind as the water seeps elsewhere, and crystals slowly grow on the inner walls of the vesicles. Within the basalts of Rio Grande do Sul, the mineral that most commonly lines the inner walls is a variety of quartz called agate. As time continues, quartz crystals slowly grow within the cavity. These crystals are irradiated with natural underground radiation, which changes the coloration and the crystals become purple amethyst.

Let’s venture into this process a little further. Given enough time, a vesicle can completely mineralize into what is called an ‘amygdaloid’. Meaning, it is completely filled with quartz and becomes a solid piece of agate. Quartz, such as this agate, is more resistant to weathering than the basalt that surrounds it. Over millions of years the basalt wears away and you are left with these round agate nodules in the soil.

And what if some of these amygdaloids didn’t quite fill up all of the way? These nodules that end up somewhat hollow on the inside are called geodes. When you cut or break open a geode, you see some of the outer agate lining, but mostly what you are looking for are the beautiful quartz crystal formations on the inside.

Amethyst geodes, that we talked about earlier, are the ones that are created very early on in the process, and are highly desired. Today, instead of waiting millions of years for erosion to take place, miners drill and blast the rock away to find these ancient vesicles containing amethyst and remove them as carefully and efficiently as possible. Some are left to be sold in their natural, beautiful color. Others might be given heat treatment to help bring out the purple hue. Some are even heat treated to the point of changing their coloration completely, which changes their classification to citrine.

So whether it be a small piece of amethyst or citrine, agate nodules or geodes, or a even an amethyst cathedral weighing up to several hundred pounds that you are hunting for, look no further! We have it all here at Western Woods Inc, with some of the highest qualities and deepest colors available. Every piece is unique and we can’t list them all here on the site, so give us a call today and see what is waiting in store for you!

Also, check out this simple infographic about amethyst we created!
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