Аннотация:The crystal structures of many borates are characterized by the modular and/or OD (“order/disorder”) character [1–3]. Because of the different types of the multiplying of the starting fundamental building block (FBB) as well as their relations in the whole structure many types of structural derivatives are possible.The larderellite-type chains are linked by the alkaline and silver cations or amomum and can be combined into the 2D-module parallel to (001) with the symmetry described by the layer group p2111.The first description of the crystal structures of the veatchite polytypes in the terms of OD theory [3] has been made on the base as the OD structures, containing one type of OD layer.The further accurate analysis [7,8] shows that the members of the veatchite family should be considered as OD structures containing three types of the OD layers equal to A, B and C modules and the whole set of polytypes can be obtained by the variation of symmetrical operation active in A and C layers.
