Silinaite has been found in two different sodalite syenite xenoliths. In the second xenolith, it was found as small fibrous clusters, poorly formed prismatic crystals and chalky to earthy powdery patches in cavities in villiaumite or aegirine.
Color is colorless to white.
Luster is vitreous to earthy. Diaphaneity is opaque to translucent or transparent. Crystal Habits include tabular crystals up to 2mm, fibrous clusters, poorly formed prismatic crystals, and chalky to earthy powdery patches. Fracture is conchoidal. Streak is white.