HOLOSYMMETRIC  CLASS (See also:

• HOLOHEDRAL

Holohedral; Dihexagonal See also:

• BIPYRAMIDAL

bipyramidal) . Intersecting in the hexad See also:

• AXIS (Lat. for " axle ")

axis are six planes of symmetry of two kinds, and perpendicular to them is an See also:

• EQUATORIAL

equatorial See also:

• PLANE

plane of symmetry . Perpendicular to the hexad axis are six dyad axes of two kinds and each perpendicular to a See also:

• VERTICAL (from Lat. vertex, highest point)

vertical plane of symmetry . The seven See also:

• SIMPLE

simple forms are: Dihexagonal bipyramid, bounded by twenty-four scalene triangles (fig . 77; v in fig . 8o) . The indices are {2131}, &c., or in See also:

• GENERAL
• GENERAL (Lat. generalis, of or relating to a genus, kind or class)

general {hikl} . This See also:

• FORM (Lat. forma)

form may be considered as a See also:

• COMBINATION (Lat. combinare, to combine)

combination of two scalenohedra, a See also:

• DIRECT

direct and an inverse . Hexagonal bipyramid of the first See also:

• ORDER
• ORDER (through Fr. ordre, for earlier ordene, from Lat. ordo, ordinis, rank, service, arrangement; the ultimate source is generally taken to be the root seen in Lat. oriri, rise, arise, begin; cf. " origin ")
• ORDER, HOLY

order, bounded by twelve isosceles triangles (fig . 70; p and u in fig . 8o); indices 110111, (202I} . . .

(holll) . The hexagonal bipyramid so See also:

• COMMON

common in See also:

• QUARTZ

quartz is geometrically similar to this form, but it really is a combination of two rhombohedra, a direct and an inverse, the faces of whit.h differ in See also:

• SURFACE

surface characters and often also in See also:

• SIZE

size .