Minerals: Hydroxides
Minerals are defined by five criteria: 1. Naturally Occurring, 2. Inorganic, 3. Solid, 4. Defined Chemical (Atomic) Formula, and 5. A unique set of physical properties.
Hydroxides
-form when a metallic element combines with water and hydroxyl (OH).

Limonite

Goethite (botryidal)

Stibconite
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Data: Pellant, Chris. Smithsonian Handbooks: Rocks and Minerals, The clearest recognition guides avaiable. A Dorling Kindersley Book.