Lapis lazuli

Metamorphic rock containing lazurite, prized for its intense blue color

Lapis lazuli (UK: ; US:) is a deep-blue metamorphic rock used as a semi-precious stone that has been prized since antiquity for its intense color. Its name originates from the Persian word for the gem, lāžward, and serves as the root for the word for "blue" in several languages, including Spanish and Portuguese azul and English azure. Lapis lazuli is a rock composed primarily of the minerals lazurite, pyrite, diopside, and calcite.

From Wikipedia, under CC BY-SA. More on occurri.