The structure of coesite is composed of SiO 4 tetrahedrons that are linked into four membered rings. The rings are then linked together into a chain-like structure. This structure is much more compact than the other members of the quartz group, except stishovite, and is reflected in the higher density and index of refraction. But this is a slow and complicated process taking thousands of years if it happens at all. It is a slow process mostly because the transformation involves the breaking of bonds and the rearrangement of atoms.
Color is colorless or white.
Luster is vitreous. Crystals are transparent to translucent. Cleavage information is unavailable. Fracture is probably conchoidal. Streak is clear.