This video explains how to construct the crystal structures of the three polytypes of the pyroxene group (clinopyroxene, orthopyroxene, and protopyroxene) using TotBlocks, a series of 3D-printed building blocks. The pyroxene group structure consists of single-chain-width modules connected by pyribole type linkages. The stacking of the O modules within the specific polytype observed influences whether the crystal structure is monoclinic or orthorhombic. These different structures affect the mineral’s optical properties, like extinction, when examined in thin section.