Final answer:
Isotropic minerals are those that do not break light rays into two plane-polarized rays, unlike birefringent materials such as calcite that split unpolarized beams of light into an ordinary ray and an extraordinary ray.
Step-by-step explanation:
The minerals that do not break light rays into two plane-polarized rays are known as isotropic minerals. Birefringent materials, like calcite, have the property of splitting unpolarized beams of light into two. These two rays are differentiated by their behavior; the ordinary ray behaves as expected, while the extraordinary ray does not obey Snell's law.
Isotropic materials, in contrast, have the same optical properties in all directions and do not exhibit birefringence. Therefore, they do not split light into two polarized rays. Anisotropic materials, like birefringent crystals, have different optical properties depending on the direction of the light passing through them, which leads to the creation of two separate rays with different indices of refraction.
Birefringent materials are significant in various applications including polarizing filters and optical stress analysis. The phenomenon of birefringence is a key concept in understanding how materials interact with light in fields like optics and material science.