1897.] Petrography. 425 
chytes is sanidine mixed with a plagioclase rich in calcium. The horn- 
blende is a yellowish-brown basaltic variety with a positive anglee v C, 
the only instance of a basaltic hornblende with this orientation. The 
different phases of the trachyte vary in composition as noted below and 
in structure. The basalts and tuffs present no unusual features. The 
rocks offer a good illustration of a petrographical province, the basalts 
representing the most basic members and the phonolites the most acid 
ones, The tephritic trachytes, with their small percentage of leucite 
are intermediate rocks. Analyses of the phonolitic (I) and the tephritic 
(II) trachytes and of the basalt (III) follows: 
SiO; TiO, AlO FeO, fe MgO CaO NaO K,O H:O P.O; SOs CO, Cl Total 
I. 65.93 42 21.83 3.62 61 2.54 7.84 6.01 .72 22 08 .03 .51= 101.17 
TI. 53.12 .25 20.48 5.13 hps 1.88 429 6.20 4.88 2.25 .43 .14 28 — 100.59 
III. 47.54 tr 17.70 75.19 6.20 5.94 9.12 4.01 143 .72 62 tr 10 07 — 98.64 
The chemical relations of these rocks to one another are represented 
graphically by means of a triangle whose angles represent 100 per cent. 
each of Na, Ca and K. The discussion upon which this method of rep- 
resentation is based cannot be entered upon in this place. 
The dykes associated with the tonalite of Meran in the 
Tyrol.—Grubenmann* gives brief descriptions of the dyke rocks con- 
nected with the tonalites near Meran. These are quartz-mica porphr- 
ites, tonalite-porphyrites, tonalite-pegmatites, diabases and hornblende- 
kersantites. The pegmatites consist of plagioclase, microcline, quartz 
and muscovite. Where in contact with gneiss, this rock has developed in 
it andalusite and garnet. 
Petrographical Notes.—The correctness of the analyses of the 
‘granular rock of Rongstock in the Bohemian Mittelgebirge having 
been called into question by Lang a new analysis has been recent pub- 
lished by Hibsch.? The results of this confirm the analysis first pub- 
lished. 
Lyons” has analyzed a large number of specimens of the soils orig- 
inating from the decomposition of Hawaiian lavas, and a series of the 
lavas from which they were derived. The results show that in the 
incipient weathering of the lavas there is a loss of silica, titanic acid, 
manganese, soda, potash and copper. The quantity of calcium present 
remains unchanged, while the percentage of magnesiaincreases. Upon 
further alteration magnesium, calcium and phosphoric acid are almost 
8 Ib., XVI, p. 185. 
*Ib., XV, p. 487. 
Hd Asher: Jour. Sci., Vol. II, 1896, p. 421. 
