What is a mineral of a light indigo-blue color, occurring in small masses, or in monoclinic crystals; blue spar. It is a hydrous phosphate of alumina and magnesia called?

lazulite — A mineral of a light indigo-blue color, occurring in small masses, or in monoclinic crystals; blue spar. It is a hydrous phosphate of alumina and magnesia. (Webster's 1913.)

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