MATHEMATICS OF PHYSICAL PROPERTIES OF CRYSTALS 



37 



Class 8 (Orthorhombic bipyramidal), center of symmetry, d = (11.08) 



(11.09) 



Class 9 (Tetragonal 



bisphenoidal) 

 -Vs is quaternary alternating 



Class 10 (Tetragonal 

 pyramidal) 

 Xz is quaternary 



Class 11 (Tetragonal 



scalenohedral) 

 .Vs quaternary, .Vi and .V2 

 binary 



Class 12 (Tetragonal 



trapezohedral) 

 Xs quaternary', Xi and .r2 

 binary 



d = 



d = 



d = 



d = 



du dn ^ 

 — dn du 



^36/ 



^0 du dn ' 



ii5 -du 



\dsi dsi dssO 0, 



/O du \ 

 ( duO ] 

 \0 dij 



^0 du 0\ 



-duO] 



^0 0/ 



Class 13 (Tetragonal bipyramidal) center of symmetry, d — 



Class 14 (Ditetragonal 

 pyramidal) 

 xs quaternary 

 .Ti and X2 planes of symmetry 



^0000 dii 0> 

 ^15 

 \dn dzi ds3 0; 



Class 15 (Ditetragonal bipyramidal) center of symmetry, d 



Class 16 (Trinonal 



pyramidal) 

 .T3 trigonal 



dn —dnO du 



— d'li ^22 rfi5 



, dzi dzi dzz 



Class 17 (Trigonal rhombohedral) center of symmetry, d — 



Class 18 (Trigonal) 



trapezohedral) 

 Xz trigonal, .ti binar}- 



d = 



Class 19 (Trigonal bipyramidal) 

 -Vs trigonal, .T3 plane of d = 



symmetry 



Class 20 (Ditrigonal pyramidal) 

 .V3 trigonal, .r2 plane of d — 



symmetry 



^^11 —dn du 

 

 <0 



' dn -rfu -2^22^ 



-£^22 ^22 -2dn 



, 0/ 



' ^15 -2^22^ 



-d22 do2 dif, 



, dzi dzi dzz / 



Class 21 (Ditrigonal scalenohedral) center of symmetry, d = 



(11.10) 

 (11.11) 



(11.12) 



(11.13) 

 (11.14) 



(11.17) 



(Quartz) 

 (11.18) 



(11.19) 



(tourma- 

 line) 

 (11.20) 



(11.21) 



I 



