Boron nitride (BN) exists in two forms. The first is a slippery solid formed from the reaction of BCl3 with NH3, followed by heating in an ammonia atmosphere at 750oC. Subjecting the first form of BN to a pressure of 85,000 atm at 1800oC produces a second form that is the second hardest substance known. Both forms of BN remain solids to 3000oC. Suggest structures for the two forms of BN.