I 



Miiiei^alogical Notices, 391 



On the Nepheline rock of the Lohau mountain ; by Dr. Heide- 

 FRiEMj (J. f. pr. Chem., 1, 500.)— This author finds' the mass of 

 the rock to consist of 45-38 p. c. of augite, 32-61 nephehne, 

 4-00 magnetic iron, 3'91 apatite, 3'43 water, 1-33 titanite, the 

 remaining 9-35 p, c. being in part olivine. The augite, a diop- 



side, consists of 



w 



^ Si - SI Oa M^ i^e »o 



52-54 0-42 25-42 17-o4 2-29 tTace=S^%1\ 



The nepheline from selected grains, afforded 



Si 51 3Pe Ca iSrg ^-a t. fi 



43-50 32 33 1*42 355 (Ml 1413 6-03 0-32 =100'S9 



Analyses of the whole stone gave 



Si Al Pe Ca Fe Mn Mg Na K ? fi 



I. 4M3 14-33 6G1 12-23 720 0-06 5 33 4 33 1*70 1.65 3-42 



II. 42*12 14-35 23-12 1300 018 6 14 4-11 213 1-63 3-42 



with chlorid of calcium 0*04, fluorid of calcium 0-27, in each, 

 and in the 2nd, 0-54 of titanic acid. 



Variolites of Drac, — Analyses and descriptions are given by 

 M. Gueymard in the Ann. des Mines, [4], xviii, 41. 



D 



of certain rocks of 



M ^M M ' ™ ■ ^^ ' ■■ ■ ^ I ^i^ ^^ ^ ^^ V ■ ■■■■ ^ ^ ^ -^ — - ^^ -— - -n — — - ^ 



[2], 540.) — This paper treats' mainly of the hornblendic rocks, 

 uiabase and diorite. The diabase of the Chalanches in Allemont 

 (Oisans) consists principally of hornblende of a deep green color, 

 lustrous and largely lamellar ; in some parts, the large crystals 

 of hornblende are so filled in with smaller, that there is little 

 room left for feldspar ; in others, the feldspar is more abundant, 

 and mixed in with the hornblende like a graphic granite. The 

 hornblende consisted of 



Si a fe <5a fig alkalies (difF.) 



hornblende, 45-3 8-0 257 12-3 6-0 IS ign. 1-4 = 100 



Oxygen 215 3-'7 '6-8 3-6 22 



The alumina appears to replace silica. 

 The feldspar afforded on analysis (p. 542} 



Si 51 Pe Ca Mg ^a K S 



^ndesite, 59-4 24-2 0-6 3-'7 trace I'O Si 1-48 = 99-78 



Oxygen 80-86 11-31 0-19 1-04 1-80 0-57 1-32 



It is hence andesite having the oxygen ratio for the protoxyds, 

 peroxyds and silica 1:3:8. The andesite is associated with 

 epidote, which is often abundant. This mineral gave on analy- 



sis (p. 543) 



51 fa Ca 



■Epidote, 40-5 302 11-2 17-7 



Oxygen 21-1 Ul 2-5 49 



