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PYBAMIDAL SYSTEM. 19 In a combination of tlie forms ill and irlkft, tbe faces of ill truncate the solid angles of the latter, in -which the edges u meet. 63. Pig. 28 shows the arrangement of the poles of the faces of the preceding forms on an octant of the sphere of projection. EIG. 28. 100 013, 032, 014, ,104 013. ,103 025, ,‘105 012, , 102 13 „ 7 125 215 ^ :1 * ll3 * 403 134 , 3H * ,/u 135 • ' * • 315 • 134 131 345 113 335 213 314 | $13 • S1 * *413 111 333 052, 031, iwi 111 *** 153* 13 .i* * *312 -615 •*° l in. H* 153 HI* 17J* _ J3J ^ ,713 502 15$ 121* * *211 *519 ’ °4I, S2 » 131* 333* * *532 *311 • 1 , 231* 831 *321 931* 241 • • 371 421 531 140 130 250 120 230 340 Ho <30 320 210 520 310 413 Of the preceding forms, those which have the simplest indices the cube 100, octahedron ill, and dodecahedron oil, occur much more frequently than the others. It does not appear that any cleavages have been observed except parallel to the laces of one or more of the formB loo, ill, oil. PYBAMIDAL SYSTEM. 6-1. In tho pyramidal system, the crystallograpbic axes make right angles with each other, and the first and second para meters are equal. 05. The form hkl is bounded by all the faces which have for their symbols the different arrangements of ± h, ± k, ± I, in which I holds tho last place. When h and k are different, they k
