The 32 Crystal Classes

Crystal system

International
symbol

Schoenflies
symbol

Space groups

Examples

Number of symmetry elements

Generating matrices
By multiplying the generating matrices with themselves and with each other, all of the elements of the group can be generated.

Independent components of rank 1 tensors1

Independent components of symmetric rank 2 tensors2

Independent components of asymmetric rank 2 tensors

Independent components of asymmetric rank 3 tensors3

Independent components of symmetric rank 4 tensors

Independent components of asymmetric rank 4 tensors

Group elements

Triclinic
a ≠ b ≠ c
α ≠ β ≠ γ

1

C1

1

1

1

S2 = Ci

2

2

Monoclinic
a ≠ b ≠ c
α ≠ 90°, β = γ = 90°

2

C2

3-5

2

m

C1h = Cs

6-9

2

2/m

C2h

10-15

4

Orthorhombic
a ≠ b ≠ c
α = β = γ = 90°

222

V = D2

16-24

4

mm2

C2v

25-46

4

mmm

Vh = D2h

47-74

47: YBa2Cu3O7-x
62: Fe3C
64: αGa
70: αS

8

Tetragonal

4

C4

75-80

4

4

S4

81-82

4

4/m

C4h

83-88

8

422

D4

89-98

8

4mm

C4v

99-110

99: PZT PbZrxTi1-xO3 x<0.52

8

42m

Vd = D2d

111-122

8

4/mmm

D4h

123-142

139: face centered tetragonal, In
141: βSn

16

Trigonal

3

C3

143-146

3

3

S6 = C6i

147-148

6

32

D3

149-155

154: α-Quartz

6

3m

C3v

156-161

161: ferroelectric LiNbO3

6

3m

D3d

162-167

167: calcite, paraelectric LiNbO3, sapphire (α-Al2O3)

12

Hexagonal

6

C6

168-173

6

6

C3h = S3

174

6

6/m

C6h

175-176

12

622

D6

177-182

180: β-Quartz

12

6mm

C6v

183-186

186: Wurtzite, ZnS

12

6m2

D3h

187-190

12

6/mmm

D6h

191-194

194: hcp, Mg, Be, Sc, α-Ti, Co, Zn, Y, Zr, Tc, Ru, Cd, Gd, Tb, Dy, Ho, Er, Tm, Lu, Hf, Re, Os, Tl, graphite, MoS2, ice Ih

24

Cubic

23

T

195-199

12

m3

Th

200-206

24

432

O

207-214

24

43m

Td

215-220

216: Zincblende, ZnS, GaAs, GaP, InAs, SiC

24

m3m

Oh

221-230

221: CsCl, cubic perovskite
225: fcc, Al, Cu, Ni, Ag, Pt, Au, Pb, γ-Fe, NaCl
227: diamond, C, Si, Ge, α-Sn, spinel
229: bcc, Na, K, Cr, α-Fe, β-Ti, Nb, Mo, Ta

48

1 Rank 1 tensors are vectors. Examples of properties described by rank 1 tensors are pyroelectricity and pyromagnetism.

2 Rank 2 tensors are matrices. Examples of properties described by rank 2 tensors are electrical conductivity, thermal conductivity, dielectic constant, magnetic susceptibility, and thermal expansion. Only the upper elements of the matrices are given because gij = gji.

3 Examples of properties described by rank 3 tensors are piezoelectricity and piezomagnetism.