312 



Dr. Walter Flight — History of Meteorites. 





Ehombic Pyramids 







Macrodomes. 







Weiss. 



Naumann. 



J8 . 



(a : oob : 6 c) .. 



• !*- 









v . 



(a : oo b : 2 c) .. 



. if « 



Q • 



.. (a : 6b: 6 c) . 



J- P 



6 + 



7 • 



(a : oob : 1 c) . 



. mP co 



o . 



.. (a : 2b : 2c) . 



i P 



2 r 



d . 



m 

 (a : oob : c ) . 



. Poo 



e . 

 a . 



f . 



. (a : b : c ) . 



. (a : 2. b : 1 c ) . 

 m m 



..(a: |b: c ) . 



P 



.. m Pn 

 .. 2 P 2 



w . 



Bracbydomes. 

 .. (a : 2b : co c) .. 



. iPco 



1 . 



.. (a : i b : c ) . 



.. 3 P3 



h . 

 k . 



... (a : b : coc ) . 



.. (a : | b : oo c) . 



. P oo 

 . 2P oo 





Ehombic Prisms. 





i 



» (a: jb:eoc) . 



. 4 P co 



n . 



.. (ooa : b : c ) . 



.. OOP 





Pinacoids. 





s 



.. (coa : | b : c) . 



.. ooP2 



a . 



.. (oo a : b : oo c) . 



. 00 P CO 



r 



.. (ooa: Jb: c) . 



.. OOP 3 



c 



.. (a : oo b : ooc) . 



. P 



The forms e, f, I, n, s, r, d, Jc, i. c, and a, are those described by 

 Rose ; the remainder were not only previously unknown on Pallas 

 olivine, but, with the exception of h and to, have not been met with 

 on chrysolite from any locality. The brachydome to has recently 

 been noticed by vom Rath 1 on the olivine of the Laachersee sanidine. 

 Although the crystal-faces of the Pallas olivine are somewhat nu- 

 merous, P 2, noticed by Descloizeaux, 2 and ooP4, as well as the 



macropinacoid b = oo P oc of other observers, have not been noticed. 

 In two of the plates accompanying the memoir the author gives eight 

 projections of the more important combinations of the above forms, 

 while in a third plate they are all graphically represented according 

 to Neumann and Quenstedt's method. 



On comparing his measurements of the faces of the Pallas olivine 

 with the numbers obtained by Mobs, von Haidinger, Scacchi, 3 and 

 himself, when examining crystals of olivine from other sources, the 

 author finds almost complete accordance between them, and deduces 

 the following numbers for the axes of the olivine crystal : 



a = 1-25928 



b - 2-14706 



c = 100000 



He then proceeds to establish their correctness by comparing in 

 detail the calculated values with those obtained by measuring the 

 meteoric olivine, and that from Egypt and Vesuvius, as well as speci- 

 mens of the mineral from other localities, investigated by Mohs and 

 von Haidinger. 



Rose i was the first to observe under the microscope the remarkable 

 structure of this olivine. On examining a section, 2^ mm. in thick- 

 ness, he noticed, even with very low powers, that it was traversed 

 by a number of straight black lines lying parallel to each other ; so 



1 G. vom Path. Fogg. Ann., 1868, cxxxv., 580. 



2 A. Descloizeaux. Manuel de Minerahgie, i., 30. ' 



3 A. Scacchi. Fogg. Ann., Ergdnzungsbandiii., 184. 



4 G. Eose. Beschreibung und Eintheilung der Meteor (ten, Berlin, 1864, 75. 



