Characteristic form for zincite crystals, n the hexagonal prism, and p pyramidal faces on it
Typical form of crystal of willemite: p the prism, r rhombohedron faces on end, ½ r a second lower rhombohedron
Plate 22
Moss agates, showing the dendritic growth of manganitic minerals, like manganite or pyrolusite
Crystal form of manganite