New examples of crystallized and amorphous borates where the ratio of BO3 triangles to BO4 tetrahedra can be calculated from the chemical formula

New examples of anhydrous and hydrous borates are presented to illustrate a recently published method for calculating the ratio of triangularly to tetrahedrally coordinated B atoms in advance from the borate formula [Z. Kristallogr. 217 (2002) 179]. Assuming that the bonding model upon which this method is based proves right, all borate phases obtained from one borate by a thermal treatment should have the same triangle-to-tetrahedron ratio. This includes all the crystallized and amorphous phases in a dehydration sequence of a hydrous borate and all the high-temperature modifications of an anhydrous borate. Selected examples for the thermal behavior of borates are discussed in view of the expected constancy of the triangle-to-tetrahedron ratio. (C) 2003 Elsevier B.V. All rights reserved.