Due to its structure, monocrystalline silicon is anisotropic, which gives it different structural and electrical properties in different plane directions.
The reflectivity (the percentage of incident energy which is reflected from a surface) for light of wavelength 540 nm varies between 29.6 and 30.2, and is slightly dependent on the direction of the incident light, that is to say, the mineral is weakly anisotropic.
(The steel deck-plate-and-ribs system may be idealized for analytical purposes as an orthogonal-anisotropic plate, hence the abbreviated designation “orthotropic.”)
Highly anisotropic solids like graphite (quasi-2D) and Bechgaard salts (quasi-1D) show anomalies in spectroscopic measurements that are attributable to the Van Hove singularities.