1. Hydroxides

2. brucite

3. brucite

4. Brucite Mg(OH)2
yellow – Mg
red – O
pink – H

5. The Oxyhydroxides (based on the formula MO(OH)
Al Fe Mn
α-AlO(OH) α-FeO(OH)
diaspore goethite
γ-AlO(OH) γ-FeO(OH)
boehmite lepidocrocite
β-FeO(OH) MnO(OH)
agakenéite manganite

6. manganite

7. diaspore

8. Goethite
goethite

9. goethite and diaspore
chains of edge-sharing octahedra, leaving vacant channels between the double chains.

10. Bauxite, a mixture of
gibbsite, diaspore
and boehmite
Bauxite

11. Gibbsite

12. Structures are similar, but in lepidocrocite and boehmite, one-half of hydroxl is replaced by oxygen.

13. boehmite

14. Romanechite
a component of the former
mineral, “psilomelane”
Ba Mn9O16(OH)4