Buergerite is a mineral species belonging to the tourmaline group. It was approved as a mineral in 1966 by the IMA and named in honor of Martin J. Buerger (1903-1986), a Professor of Mineralogy at the Massacusetts Institute of Technology and a pioneer of crystal structure analysis. There are only three know locations world wide that Buergerite has been found at: Mexico the type locality, Brazil, and the Czech Republic. A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... The molecular mass of a substance (less accurately called molecular weight and abbreviated as MW) is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon-12). ... In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite planes, creating smooth surfaces, of which there are several named types: Basal cleavage: cleavage parallel to the base of a crystal, or to the plane of the lateral axes. ... Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer. ... A calcite crystal laid upon a paper with some letters showing the double refraction Birefringence, or double refraction, is the decomposition of a ray of light into two rays (the ordinary ray and the extraordinary ray) when it passes through certain types of material, such as calcite crystals, depending on... Minerals are natural compounds formed through geological processes. ... In physics, density is defined as mass m per unit volume V. Mathematically, it is expressed as where, in SI units: Ï (rho) is the density of the substance, measured in kg·m-3 m is the mass of the substance, measured in kg V is the volume of the substance... Minerals are natural compounds formed through geological processes. ... The tourmaline mineral group is chemically one of the most complicated groups of silicate minerals. ... The International Mineralogical Association (IMA) is an international group of 38 national societies. ... In scientific classification, a type is a specimen or description that corresponds to a taxon (a group of organisms), and helps to identify which organisms may be referred to with that name. ...
Buergerite is more easily confused with the lesser known tourmaline, dravite.
Buergerite, when first discovered, was considered to be an unusual variety of schorl, another sodium iron tourmaline.
To compensate for the extra +3 charges (one extra charge from each of the three iron ions in the formula) buergerite must substitute three of the four hydroxides (with a -1 charge each), that are normally present in a typical tourmaline, for three oxygens (each with a -2 charge) in order to balance the formula.
A study into a large suite of tourmalines indicates that the B-O2 and B-O8 bond lengths vary due to the chemical composition of the tourmaline, though the average B-O distance and the amount of B remain constant.
Average B-O2 and B-O8 bond lengths for schorl are 1.354 and 1.384 Å and for buergerite are 1.380 and 1.374 Å, respectively.
Because of the significant difference in bond-lengths, crystal-structure data related to the B-site of tourmalines in question can be used to verify whether the assumption made during normalization are reasonable, especially in regards to the buergerite vs.
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