Turkish Stick Agate - Quartz Cosplaying as Aragonite

Posted by Maranda Powers on

It's pretty obvious where stick agate gets it's name, but I am always curious about how stones are formed. It looks like a jumble of needles frozen in ice. How does that happen?

To talk about how we end up with the tiny wonders that are stick agates, we need to talk about pseudomorphs first. You are probably familiar with a few already but may not have realized it - fossilized dino bone and petrified wood are both pseudomorphs.

The name alone gives us a great place to start, it literally translates to “false forms”. That doesn’t mean that these stones are fake, it means that the minerals making up these stones are appearing in a form that they don’t naturally take, their form is false.  In the case of fossil dino bones, the minerals that make up those fossils don’t naturally form into the shape of a bone. Instead, when the minerals encountered that dinosaur bone, they gradually replaced the organic material and took on the shape, or form, of the original bone. They replaced the original, in a sense they made a copy. In some cases an incredibly detailed, down to the individual cell copy! This doesn’t just happen with organic materials though, minerals can be pseudomorphs of other minerals as well.

Let’s say some water chock full of dissolved minerals seeps its way into a cavity in a rock somewhere, maybe somewhere like Turkey. The minerals in this water start to deposit inside the cavity and they just happen to be the right mix to make aragonite, and a beautiful cluster of long, hollow, crystals forms because that’s one of the natural shapes that aragonite takes.

an aragonite cluster from Spain - photo credit

Then, since the Earth is always moving and shifting, something changes in the local conditions and now the minerals dissolved in the water that is filling our cavity are different. When they are deposited, they form quartz instead of aragonite.  As the quartz slowly precipitates out of the solution, it fills the cavity. It doesn’t just surround or encase the aragonite though, it gradually fills in the hollow areas inside the aragonite as well. Very, very, gradually.

After a brain-breaking amount of time, the quartz has completely filled in the cavity, filled up the spaces inside those aragonite "sticks" and taken on the form of the aragonite crystals, a false form. A false form that we call stick agate. And since this all happened in a place that we will eventually call Turkey, the resulting stone is called Turkish stick agate. Lucky for us, the quartz surrounding and filling the crystalline shapes is often translucent, so we get to see inside the stone,even inside some of the “sticks”, and really get a sense of how these little treasures were formed.

a polished slice of Turkish stick agate - I love how you can see the outside edge of the cavity in which this one formed and the layers of deposited quartz

And we all know what the key to my heart is: a gorgeous stone with the history of it's geologic formation on display, and a tiny little science lesson thrown in :)

 It's such a joy to work with stones that impart a sense of wonder like these ones do. I know it's an extra special collection when I catch myself sitting at my work bench NOT working because I'm just staring at the stones trying to fathom deep time, lol!  And nope, I am not high or drunk during these revelries ;) I just really like rocks!


If you find them as intriguing as I do, head on over to my shop to see what's available.

Thanks for reading, friends. I am forever grateful for you!

<3 Maranda

*** I am not a scientist or an expert on any of the topics I cover on this blog, I am just an enthusiastic rock and fossil fan trying to spread the love. I encourage you to do your own reading and research on any topics that might strike your fancy. If you are an expert and would like to gently correct me, please do! You can reach me via email at maranda@powershandcrafted.com. You can also reach out to tell me how I totally nailed it, or just to say hi, or to show me some cool rock you found.***


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