Geology and Mineralogy. 393 
duction of gold at foreign localities. Some of the other topics 
discussed in the report are: the iron ores and iron industries of 
manufacture; mud voleanoes and Colorado Desert; diamonds in 
California. The A pend. —_— S papers on the forest trees of 
poral ia by A. Kello . Rs Wt 
obi : 
se 
description of the various voleanic rocks collected and studied by 
him and of the accompanying minerals, As older eruptive rocks 
are recioghthed foyaite, syenite, diorite and diabase; as younger 
eruptive rocks: leucitite (rare), phonolite, tephrite, basanite, 
Piagioclase -basalt, nephelinite, nepheline-basalt, limburgite, pyrox- 
ite. The author has applied the various modern me 
the examination of the different rocks, a ud his descriptions are 
age amount in mae they enter. The rock salad pyrononite i is 
described as a limburgite, or magma-basalt, withont olivine, in 
other words, a rock consisting essentially of augite, magnetite, and 
@ glassy base, with, as an accessory, haiiynite and rarely plagio- 
arr nephelite and olivine 
econdary mineral, occurring at several spots on the 
island a Aiode Antonio, erevices on the lava, the author de- 
Scribes a new member ‘of the alum group, ander the name of 
Dumreicherite. Yt forms crusts on the lava, with fibrous struc- 
ture. An optical examination showed it to be probably mono- 
clinic ; this result was s confi st ; 
t 
cr ystallization, An analysis by F. Kertscher gave; 
SO; Al,Os MgO H,0 
36°65 T14 11°61 45°01 Na, Cltr. = 10041 
- se age Speke formula is 4MgSO, + Al,S,O,, +36 aq. 
Poster: ing Quartz “Cr rystals.— =r. W. E. Hrppen has 
