The 141 degree oxygen is unique to Minit style molecular models & is especially useful in building various silicate structures. Our best example is this chemically correct zeolite mineral structure model.
This atom can be used with any of the tetrahedral atoms to produces silicate layered structures found in clays & other materials.
Most zeolite molecular models use just the tetrahedral atoms to build the general cage structure. The 141o Minit oxygen atom allows you to build a more "anatomically correct" aluminosilicate as can be seen in this Minit zeolite crystal structure model.
|Minit Zeolite A Structure Model with Oxygens, 532 atoms