What's the difference between hornblende and tourmaline?

Hornblende

Definition:

• (n.) The common black, or dark green or brown, variety of amphibole. (See Amphibole.) It belongs to the aluminous division of the species, and is also characterized by its containing considerable iron. Also used as a general term to include the whole species.

Example Sentences:

• (1) There's limestone and sandstone to the north, but Aswan's bedrock is hornblende granite.
• (2) Xanthine oxidase was immobilized on cellulose, Sepharose, hornblende, Enzacryl-TIO, and porous glass.
• (3) These fungi were incubated with the following iron-containing minerals: augite, hornblende, biotite, magnetite, hematite, and the igneous rock granodiorite.

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.