This video explains how to construct the crystal structure of the chlorite group using TotBlocks, a series of 3D-printed building blocks. The chlorite group’s crystal structure consists of T-O-T layer modules which alternate with O layer modules. Essentially, the chlorite group can be thought of as a 2:1 phyllosilicate with an added brucite layer as the interlayer. Subtle differences in the interlayer bonds of chlorites and micas lead to their different physical properties of brittleness and elasticity.