Lapis lazuli is a composite rock primarily composed of calcite, lazurite, and pyrite, and serves as the birthstone for December, associated with the zodiac signs Taurus and Sagittarius. It is known for promoting inner truth, positive magic, self-confidence, and has healing properties that boost the immune system, benefit the respiratory and nervous systems, and alleviate insomnia and depression. Additionally, lapis lazuli purifies the blood and supports various organs including the throat and thyroid.