Polyhedroid Agates
Courtesy Ben Edwards Collection
Courtesy 2009 Gem Shop Calendar
Polyhedroid Agates ....These are one of nature’s great unexplained formations. These geometric beauties were only found for a short time in the 1970’s and only in one location in the world. It is fitting that some of the most desirable agates in the world come from the greatest agate producing country, that being Brazil. These were located in Paraiba the only state in Brazil that ever produced any of these specimens. These stunning agates formed in geometric pattern shapes rather than the more common round or oval agate shape.
The theories of formation of these agates are still an ongoing evaluation among geologists. The most agreed upon formation theory seems to be that the sharp geometric shapes are thought to have been formed in the voids between interlaced crystals of Barite, or possibly Calcite crystal formations. The agate nodules can be solid or hollow and the best grades have distinct, colorful fortification agate bands that follow the typically triangular or trapezoidal shape of the Polyhedroid Agate.
They are some of the highest quality agates available, and are able to be polished to the highest mirror glaze finish that quality agates can obtain. These agates rarely have fractures or other imperfections. Most nodules are quartz with black, gray, white being the predominant colors of the Polyhedroid agates. Shapes can be a variety of geometric forms with the right triangle or the equilateral triangle shape being the most desirable shapes.
One cannot help but wonder if Euclid, the father of Geometry found some of these agates or maybe nature made these just to prove Euclid’s theorems. The Polyhedroid Agate makes the best agate show piece and conversation piece in any collection. These are very rare and expensive….but like they say…”You get what you pay for!” Polyhedroid Agates are one of our favorites!
We have spent the better part of the last 30 years collecting Polyhedroid Agate specimens. We sell a few polished , cut or rough ones from time to time. As we get older we are realizing that we probably will never be able to cut and polish all the wonderful Polyhedroid Agates we have collected, so we have decided to sell off a few of what we have collected.
This rare matrix specimen which shows the Polyhedroid agate formation in crystalline calcite, supporting the current best formation theories. You can see the calcite blades and agate shapes pointed out with the arrows in the photo shown on the left. This photo lends some insight into how some of these legendary polyhedroids are formed.
We will be listing here Polyhedroid Agates which are geometrically shaped, mostly with quartz centers, but can have small agate banding in the center. We will also be listing some smaller good to AA grade (Jewelry grade) agates. These all will sell based on current market pricing.
When these agates are light colored on the outside, the interior will mostly be clear quartz. The amount of darkness in the exterior skin will give you an idea of how much grey or black shading is inside these rare agates. If you look at the photos above and at our listings you will see the wide array of possibilities for the interiors of these agates. You never know until you cut one open what surprises lie hiding inside. We have always been fascinated with Brazilian Agates but especially so with these Rare Polyhedroid Agates. We feel very lucky to have some to offer you for your collection and maybe even some for you to cut and polish.