What's the difference between pleochroism and tourmaline?

Pleochroism

Definition:

• (n.) The property possessed by some crystals, of showing different colors when viewed in the direction of different axes.

Example Sentences:

• (1) X-ray pleochroism is observed near the Se K absorption edge in a monoclinic crystal of selenolanthionine monohydrate using linearly polarized synchrotron radiation and is explained by a simple molecular-orbital model.

Tourmaline

Definition:

• (n.) A mineral occurring usually in three-sided or six-sided prisms terminated by rhombohedral or scalenohedral planes. Black tourmaline (schorl) is the most common variety, but there are also other varieties, as the blue (indicolite), red (rubellite), also green, brown, and white. The red and green varieties when transparent are valued as jewels.

Example Sentences:

• (1) Facebook Twitter Pinterest Illustration: Ciara Phelan September wasn’t tourmaline; it was the release of a videotape that showed the American football player Ray Rice knocking out his fiancée in a lift, and a renewed public conversation about domestic violence, accompanied by #WhyILeft and #WhyIStayed.