DUMORTIERITE IN QUARTZ

ABOUT THE SPECIMEN

Clear quartz sitting on top of and together with a mass of fibrous, deep blue dumortierite. This specimen is in fantastic condition, and the clarity of the quartz allows one to see the crystallization of the dumortierite super clearly - the most desirable attribute of this combination.

MORE INFO

Operated primarily to extract blue quartzite as an industrial raw material, the Vaca Morta quarry sits within the São Francisco Craton in western Bahia, where Proterozoic metasedimentary sequences underwent pervasive boron metasomatism - the process responsible for concentrating the aluminum borosilicate dumortierite throughout the host quartzite. The blue color is an intrinsic structural feature of the species tied to iron substitution and charge-transfer interactions rather than a trace impurity, which accounts for its intensity and consistency. First recognized as a collector locality around 2013, Vaca Morta rapidly established itself as the definitive world source for euhedral quartz crystals containing acicular dumortierite inclusions - a combination that exists elsewhere only as a rarity. Habit ranges from tightly packed fibrous blue stripes running parallel to the quartz c-axis to radiating sprays trapped within water-clear terminated prisms, the latter being the most sought-after form. Massive dumortierite on milky quartz matrix is more common and considerably more affordable than the inclusion-in-crystal material, which requires exceptional host clarity to display effectively. The quarry continues to operate intermittently, but fine inclusion specimens have never been abundant relative to demand.