Which of the following correctly defines spectrolite?

Spectrolite is correctly defined as a variety of labradorite, a member of the feldspar mineral group. It is specifically noted for its distinct play of colors, known as labradorescence, which displays a vibrant spectrum of colors when viewed from different angles due to its unique crystal structure. This phenomenon occurs because of the diffusion of light within its layers, leading to the colorful displays that are characteristic of spectrolite.

Unlike quartz, which has its own unique properties and characteristics, or organic gemstones that derive from biological processes, spectrolite is a naturally occurring mineral. It is also distinct from various forms of jade, which are entirely different materials with separate formation processes and chemical compositions. Recognizing spectrolite as a type of labradorite emphasizes its origins and ties to the broader category of feldspar minerals, while also highlighting its prized aesthetic qualities leveraged in jewelry and decorative uses.