Editing Boron nitride (section)

=== Wurtzite form (w-BN) ===
The [[Wurtzite crystal structure|wurtzite]] form of boron nitride (w-BN; point group = C<sub>6v</sub>; space group = P6<sub>3</sub>mc) has the same structure as [[lonsdaleite]], a rare hexagonal polymorph of carbon. As in the cubic form, the boron and nitrogen atoms are grouped into [[tetrahedra]].<ref>{{cite book | author = Silberberg, M. S. | title = Chemistry: The Molecular Nature of Matter and Change | edition = 5th | location = New York | publisher = McGraw-Hill | year = 2009 | page = 483 |isbn=978-0-07-304859-8}}</ref> In the wurtzite form, the boron and nitrogen atoms are grouped into 6-membered rings. In the cubic form all rings are in the [[chair configuration]], whereas in w-BN the rings between 'layers' are in [[boat configuration]]. Earlier optimistic reports predicted that the wurtzite form was very strong, and was estimated by a simulation as potentially having a strength 18% stronger than that of diamond. Since only small amounts of the mineral exist in nature, this has not yet been experimentally verified.<ref>{{Cite web |url=https://www.newscientist.com/article/dn16610-diamond-no-longer-natures-hardest-material/ |title=Diamond no longer nature's hardest material |last=Griggs |first=Jessica |date=2014-05-13 |website=New Scientist |access-date=2018-01-12}}</ref> Its hardness is 46 GPa, slightly harder than commercial borides but softer than the cubic form of boron nitride.<ref name="ReferenceA" />

<gallery mode="packed">
File:Boron-nitride-(hexagonal)-side-3D-balls.png|Hexagonal form (h-BN)<br/>[[Hexagonal crystal family|hexagonal]] analogous to [[graphite]]
File:Boron-nitride-(sphalerite)-3D-balls.png|Cubic form (c-BN)<br/>[[sphalerite]] structure<br/> analogous to [[diamond]]
File:Boron-nitride-(wurtzite)-3D-balls.png|Wurtzite form (w-BN)<br/>[[Wurtzite crystal structure|wurtzite]] structure<br/>analogous to [[lonsdaleite]]
</gallery>