# Dana classification system

Dana's classification is a mineral classification developed by James Dwight Dana. It is based on the chemical composition and structure of minerals. It is mainly used in English-speaking countries, especially in the United States.
The mineral classification used by the International Mineralogical Association is the Nickel-Strunz classification.

## History

The classification of minerals was based on chemical composition by Dana in the fourth edition (1854, in two volumes) of his book System of Mineralogy. For the 20th century, this classification was completed thanks to scientific progress, particularly in the field of crystallography. In 1941, Karl Hugo Strunz used it to construct his classification. Dana's original classification was further developed, and a new classification was published in 1997.

## Classification structure

Minerals are arranged in a hierarchical system. Each mineral has a classification number, made up of four numbers separated by dots, enabling unambiguous identification even when minerals are known by several names (synonymy). The first number represents the mineral class. The second number represents the mineral type, in some cases taking into account its atomic structure. The third number represents a group of minerals of similar structure. The fourth number gives the unambiguous identification of the mineral.

## Example

Kieserite group.
* 29. Acidic and normal hydrated sulfates
** 29.06.: acid and normal hydrated sulfates of the formula AXO$_4$-x(H$_2$O)
*** 29.06.02.: kieserite group (monohydrates)
**** 29.06.02.01.: kieserite MgSO$_4$-(H$_2$O), space group C2/c
**** 29.06.02.02.: szomolnokite FeSO$_4$-(H$_2$O), space group A2/a
**** 29.06.02.03.: szmikite MnSO$_4$-(H2O), space group A2/a
**** 29.06.02.04.: povinite (Cu,Fe,Zn)SO$_4$-(H$_2$O), space group P1
**** 29.06.02.05.: gunningite (Zn,Mn)SO$_4$-(H$_2$O), space group A2/a
**** 29.06.02.06.: dwornikite (Ni,Fe)SO$_4$-(H$_2$O), space group C2/c
**** 29.06.02.07.: cobaltkieserite CoSO$_4$-H$_2$O, space group C2/c

## Mineral classes

| Elements | Chemical element |
| Sulfides and sulfosalts | 01. Sulfides 02. Sulfosalts |
| Oxides and hydroxides | 04. Basic Oxides 05. Oxides containing uranium and thorium 06. Hydroxides and oxides containing hydroxylation 07. Multiple oxides 08. Multiple oxides containing niobium, tantalum and/or titanium |
| Halides | 09. Halogenides 10. Oxyhalides and hydroxyhalides 11. Complex halides - aluminofluorides 12. Compound halogenides |
| Carbonates, nitrates and borates | 13. Acid carbonates 14. Non-hydrated normal carbonate 15. Normal hydrated carbonate 16a. Carbonate containing hydroxyl anion or halogen 16b. Carbonate containing hydroxyl anion or halogen 17. Compound carbonates 18. Simple nitrate 19. Nitrates containing hydroxyl anion or halogens 20. Compound nitrate 21. Non-hydrated and hydrated iodate 22. Iodates containing hydroxyl anion or halogen 23. Compound iodate 24. Non-hydrated borate 25. Non-hydrated borate containing hydroxyl anion or halogens 26. Hydrated borate containing hydroxyl anion or halogens 27. Compound borate |
| Sulfates, chromates and molybdates | 28. Acidic and normal non-hydrated sulfates 29. Acid and normal hydrated sulfates 30. Non-hydrated sulfates containing hydroxyl anion or halogens 31. Hydrated sulfates containing hydroxyl anion or halogens 32. Compound sulfates 33. Selenates and telluratess 34. Selenites, tellurites and sulfitess 35. Non-hydrated chromates 36. Hydrated chromates |
| Phosphates, arsenates and vanadates | 37. Non-hydrated acid phosphates 38. Non-hydrated normal phosphates 39. Acid phosphates, hydrated 40. Normal phosphates, hydrated 41. Non-hydrated phosphates containing hydroxyl anion or halogens 42. Hydrated phosphates containing hydroxyl anion or halogens 43. Compound phosphates 44. Antimoniates 45. Acid and normal antimonites, arsenites, and phosphites 46. Basic or halogen-containing antimonites, arsenites, and phosphites 47. Vanadium oxysalts 48. Molybdates and tungstates 49. Basic and hydrated molybdates and tungstates |
| Organic minerals | 50. Organic minerals |
| Silicates and germanates | |
| Nesosilicates | 51. Nesosilicates containing only isolated [SiO$_4$] tetrahedral groups 52. Groups of [SiO$_4$] tetrahedra with O, OH, F, and H$_2$O 53. Groups of [SiO$_4$] tetrahedra with other anions or complex cations 54. Borosilicates and some beryllosilicates with [BO$_3$]. |
| Sorosilicates | 55. Groups Si$_2$O$_7$, generally without additional anion 56. Groups Si$_2$O$_7$ with O, OH, F, and H$_2$O 57. Insular (Si$_3$O$_{10}$) and larger non-cyclic groups with Si$_3$O$_{10}$ 58. Insular, mixed, isolated, and larger tetrahedral groups |
| Cyclosilicates | 59. Three-membered rings [Si$_3$O$_9$]. 60. Four-membered rings [Si$_4$O$_{12}$]. 61. Six-membered rings [Si$_6$O18]. 62. Eight-membered rings [Si$_8$O$_{24}$]. 63. Cyclosilicates with condensed rings 64. Rings with other anions and isolated [SiO$_4$] groups |
| Inosilicates | 65. Unbranched simple chains, periodicity W=1 66. Unbranched double chains, periodicity W=2 67. Unbranched chains, periodicity W > 2 68. Structures with variable chain widths 69. Chains branched to other chains or loops 70. Tubular or columnar structures |
| Phyllosilicates | 71. Six-member ring layers 72. Infinite layers without six-member rings 73. Condensed tetrahedron layers 74. Modulated layers |
| Tectosilicates | 75. Tectosilicates 76. Aluminum and silicon networks 77. Zeolite group |
| Unclassified silicates | 78. Unclassified silicates |