1. Carbonates and Nitrates

2. CaCO3,, Calcite
CaMg(CO3)2
Dolomite
CaFe(CO3)2
Ankerite
MgCO3, Magnesite
FeCO3, Siderite
Molecular %

3. Calcite group minerals
CaCO3, Calcite
MgCO3, Magnesite
FeCO3, Siderite
ZnCO3, Smithsonite
MnCO3, Rhodochrosite
CaCO3, Calcite
FeCO3, Siderite
Hexagonal _
Space group R32/c
Hexagonal
Point group: 32/m c
Cations in 6-fold coordination

4. Dolomite-group minerals
CaMg(CO3)2, Dolomite
CaFe(CO3)2, Ankerite
CaMn(CO3)2, Kutnahorite
Hexagonal _
Space group R3 c
Cations in 6-fold
coordination

5. Crystals of minerals
of the calcite group

6. Aragonite group minerals
Cations in 9-fold coordination
CaCO3, Aragonite
CaCO3, aragonite
BaCO3, witherite
SrCO3,strontianite
PbCO3,cerrusite c
Orthorhombic
Space group Pmcn

7. Crystals of minerals of the aragonite group
Cyclic twins: combinations of
pseudohexagonal prisms and
dipyramids
Combinations of orthorhombic
prisms and dipyramids
Crystals of minerals of
the aragonite group

8. Reconstructive phase transition

9. calcite

10. calcite

11. calcite Double refractions twinning Double refraction
Twinning in “dog tooth spar”

12. magnesite

13. siderite

14. smithsonite

15. rhodochrosite

16. aragonite
aragonite twins

17. Aragonite shells

18. witherite

19. strontianite

20. cerrusite
Cerrusite twins

21. dolomite

22. Il Dolomiti,
The Dolomites
of northern Italy

23. ankerite

24. Monoclinic carbonates
malachite Cu2CO3(OH)2
azurite Cu3(CO3)(OH)2

25. malachite

26. malachite b
Cu(O,OH)6 edge-sharing octahedra forming chains. The three dots represent carbonate groups. a

27. azurite

28. azurite c
Chains of CuO2(OH)4 and CuO4(OH)4 octahedra linked by edge-sharing. Chains are cross linked by carbonate groups (in red). b

29. Nitrates nitratite (soda niter) NaNO3 – isostructural with calcite
niter (saltpeter) KNO3 –
isostructural with aragonite

30. nitratie

31. Niter (saltpeter)