Jasper or Agate: What’s in a [Trade] Name?

Posted by Dakota Stones on 9/15/2019 to Articles

The names the bead industry uses for materials aren’t always scientifically correct or precise. The best example in recent years is the widespread use of “Cacoxenite” to describe a stone that’s a blend of Quartz and other minerals, including Cacoxenite. More generally, this issue appears when “Agate” and “Jasper” seem to be used by different vendors to describe the same material.

HOW DO YOU KNOW WHICH IS ACCURATE?

The easiest test it visual. Put light behind the material. If you can see light through it, it’s Agate. If you can’t, it’s Jasper.

It’s an easy test, but the underlying science is more complex. Let’s start with Quartz basics. Quartz is one of the most abundant materials on the planet with two major varieties; macrocrystalline and cryptocrystalline. Macrocrystalline Quartz includes the varieties forming in visible points and clusters. Amethyst, Smoky Quartz, and Citrine all fall into this category. Cryptocrystalline Quartz crystals are only visible under magnification.

Within the realm of cryptocrystalline quartz we start to see where and why the confusion occurs. When viewed under a microscope, Quartz crystals will either appear parallel to each other or they will appear randomly. When the crystals are parallel, it’s considered a “fibrous” cryptocrystalline. If the crystals are not, it’s considered “grainy” cryptocrystalline.

On a microscopic level, you can see the difference between Jasper and Agate based on their crystal structure. Agate is a fibrous cryptocrystalline, which is visible to the naked eye in its areas of translucence. Jasper is grainy cryptocrystalline, and this manifests to the naked eye in its opacity.

Within the bead industry, confusion arises when long-accepted trade names conflict with science. Language can also play a part in the misidentification of a stone. Most stones are not mined and cut in the same country, and not every member of the gemstone mining and manufacturing community is a stone, mineral, or geology expert fluent in multiple languages.

At Dakota Stones, we choose to use trade names for materials in most cases. We make every effort to identify both other common names for a stone, as well as to fully disclose the composition of a stone within each product description.

Note: Not all opaque material is Jasper, nor is all translucent material Agate. This article is meant to help readers understand why similar materials may bear different names or have characteristics at odds with them.

Jasper or Agate: What’s in a (Trade) Name?

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