Pietersite

What do you get when you cross a hawk with a tiger? Read on to find out!

This simple-looking stone has a rather complicated geological history. So, please, bear with me as we explore the nuances of this fascinating rock and learn the answer to the above question.

When minerals form in the earth, they usually have a crystalline structure of some sort. A "crystal" is merely a geometric shape into which the mineral grows, such as the one pictured at right. Whether it forms as a cubic, trigonal, hexagonal, etc. structure is based on the peculiarities of the chemical bonds that are formed between the different elements that comprise the mineral. Anyone interested in crystallography, the study of the structure of crystalline solids, can start with this article, but please finish reading my article first! 😁

Sometimes, however, crystals form in such tiny structures that they cannot be seen with the naked eye, and those are referred to as "microcrystalline" structures. Others are so small that they are not even discernible in a typical microscope, and those are called "cryptocrystalline" structures. Such is the case with this stone, but it gets even more interesting...

One mineral I have not written about yet is crocidolite, a family of minerals that includes Tiger's Eye, Hawk's Eye, and others. Crocidolite is a mineral that forms in long fibers which can reflect flashes of light. This stone was once composed of crocidolite fibers, but over time that crocidolite was replaced by quartz.

So, this rock was once crocidolite — both Tiger's Eye and Hawk's Eye varieties, swirled together — which was then replaced by cryptocrystalline quartz (which is known as "chalcedony") so, it is now a brecciated chalcedony. The particular variety of brecciated chalcedony was first discovered by Sid Pieters, so it is named Pietersite, in his honor.

If that isn't an interesting story behind a rock, I don't know what is!

Pietersite was originally discovered in Namibia, Africa. A small deposit was found in China later, but the vein was depleted quickly. Currently, Namibia is the only place on earth that is known to have this relatively rare mineral.

I did not know anything about this mineral when I got the sample I have. I just saw it in a shop, thought it was pretty, and recognized it as something I did not already have in my collection. After reading about its rarity, I am thrilled now, in hindsight, to have had the opportunity to purchase it! As with many of my mineral specimens I obtained long ago, I do not remember what I paid for it, but I am sure it was less than USD $15, maybe even around USD $10, and probably 18 years ago or more.

FireMountainGems says "Because its swirling colors resemble a storm, pietersite is known as tempest stone."  So, this is like holding a storm in the palm of one's hand! 😁