What is the difference between moonstone and white crystal?

Mineralogically speaking, moonstone is a feldspar, an aluminum silicate. And white crystal is silica.

Structurally speaking, moonstone is composed of twin crystals of potassium and albite arranged alternately to form a lattice structure. White crystal has a uniform silica structure.

In appearance, moonstone has an obvious floating blue or white luster, which is caused by Rayleigh scattering. White crystal doesn't have it, it's transparent.

In terms of hardness, moonstone is lower than white crystal.

The refractive index of moonstone is 1.518~1.526. And white crystal 1.544-1.553.

Moonstone can have optical effects such as cat's eye effect, halo effect, moonlight effect, etc., while white crystal does not.

In appearance, moonstone has very low transparency, while white crystal is very transparent.