This video explains how to construct the crystal structure of the brucite group using TotBlocks, a series of 3D-printed building blocks. The structure of the brucite group consists of O layer modules joined together widthwise to form infinite sheets. Based on the charge of the component cations of the O layer, the modules can be either dioctahedral or trioctahedral. Other layered minerals with O modules display similar patterns between dioctahedral and trioctahedral modules. The sheeted nature of the O modules leads to a platy habit and basal cleavage within this mineral group.