PYRAMIDAL CLASS (See also:

• HEMIMORPHIC

Hemimorphic-See also:

• TETARTOHEDRAL

tetartohedral)  . Here the only See also:

• ELEMENT (Lat. elementum)

element of symmetry is the tetrad See also:

• AXIS (Lat. for " axle ")

axis . The pyramids of the first lhhll second {hol} and third{hkl} orders have each only four faces at one or other end of the crystal, and are See also:

• HEMIMORPHIC

hemimorphic . All the See also:

• SIMPLE

simple forms are thus open forms . Examples are See also:

• WULFENITE

wulfenite (PbMoO4) and See also:

• BARIUM (symbol Ba, atomic weight 137'37 [0=16])

barium antimonyl dextrotartrate (Ba(SbO)2(C4H40o).H20) .