Complex sentence: The ordinary passes undeviating through the crystal and show normal optical properties (reflection, refraction), but the extra-ordinary ray passes deviating through the crystal.Non-crystalline materials have no double refraction and thus, no optic axis.
Split into simpler sentences: The ordinary passes undeviating through the crystal and show normal optical properties (reflection and refraction), but the extra-ordinary ray passes deviating through the crystal. Non-crystalline materials have no double refraction and thus, no optic axis.