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Product Description
Polyhedroid Agate Rare Polished Rock Paraiba Brazil
This is a gorgeous rare Polyhedroid Agate that is slabbed and polished on one face, left natural rough elsewhere, and it is 6.75 inches by 1.7 inches and 1.75 inches thick.
It has 1 natural crystal vug or pocket that goes all the way through and a couple tiny little natural vugs near it.
Unlike the typical smooth, concentric banding seen in most agates, Polyhedroid Agates feature bands that have sharp, angular formations that resemble polyhedrons resulting in striking, geometric patterns.
Polyhedroid Agates are very rare. They were only found in one location in the world, the Paraiba region in northeastern Brazil. There has been no mining of Polyhedroid Agates in recent years. Most were mined during the 1970s.
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.
The geometric nature of polyhedroid agate is believed to result from the formation of gas bubbles in the volcanic rock, which are then transformed into polyhedral cavities through crystallization processes. As the agate forms, the silica deposits mimic the shape of the cavity, which in the case of polyhedroid agates, results in the sharp, multi-sided shapes that give the stone its name.
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.
