The Mineral buergerite
Buergerite is a rare member of the Tourmaline group. It was first discovered in 1966, and its locality was subsequently forgotten until the noted Mexican mineral collector Dr. Miguel Romero hired two exploration geologists to search and find the deposit. Subsequent finds have yielded very little material, and good specimens of this rare form of Tourmaline remain difficult to obtain. Buergerite is named in honor of Martin J. Buerger (1903-1986), a prominent mineralogist and professor of mineralogy at Massachusetts Institute of Technology.
Chemical Formula
NaFe2+3Al6(BO3)3Si6O18O3F
Color
Bronze-like dark yellowish brown to nearly black.
Crystal Habits
Crystals are usually three sided prisms, and are usually short and stubby, though elongated crystals exist as well. Terminations can be both simple and complex, and growth layers are often present. Occurs in columnar aggregates and as dense agglomerated prisms.
Other Names
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Fluor-buergerite
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Fluor-buergerite is the IMA-recognized name of Buergerite since 2011. The renaming was due to recent analysis of fluorine present in the chemical structure of this mineral at the type locality. Most collectors still refer to this mineral as Buergerite, and have not adopted the new, lengthier name.
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Uses
Buergerite, being a very rare form of Tourmaline, is an expensive and cherished collectors mineral.
Noteworthy Localities
The type locality of this mineral where all collectible specimens have come from is Mexquitic, in San Luis Potosí, Mexico. The chemical makeup of Buergerite suggests that it should be more globally distributed, and although subsequent localities have since been discovered, they have not produced any collectible specimens of interest.
Common Mineral Associations
Opal, Biotite, Feldspars
Distingushing Similar Minerals
Dravite - Does not occur in igneous rhyolite environments.