d 
Mineralogy and Geology. ) 421 
Figure 24. Xenotime, from slays pple oe 25. 
from crystals received from Prof. Lewis R. Gibbes 
of Charleston, South Car aie na. 
mination to a e-sided summit by oscillation 
with a scalenohedral form, (probably 1%,) is sub- 
sequently terminated b crystal of the nail- 
F igure 26. Dolomite, from Hoboken, New Jer- 
sey. The crystals are glassy, a third to a quarter 
of an inch across, and occur in cavities in massive 
dolomite 

2. Beitriige zur Kenntniss der Eisenhohofen- Sela tens nebst einem 
geologischen Anhange, (on Iron Furnace Slags, etc.) ; by J. F. L. Havs- 
MANN. 102 pp. 8vo. (From Busnes des Gott. Ver. Bergm. Freunde.) 
Gottingen, 1854.—Prof. Hausmann has. sporinees largely to our 
knowledge of the slags of reins and presented the bearing o 
subject on the origin of minerals. This recent “tt contains descrip- 
tions and ng ea various furnace products, and an application of 
the facts to Geo 
)A 
(1. 
described by M. Koch, ‘Beit, 2 r Kenntniss kryst. Sica 
Gottingen, 1822, 8vo, p. 40-81). ik occurs in 6-sided prisms, tabular 
or elongated, with the terminal edges sometimes removed, producing 
Tarely a Six- sided pyramidal termination. Color whitish, gray, yellow- 
ish, brownish, greenish. G.=—2°72. H.=-7. Translucent, to sub- 
translucent. Lustre waxy, weak. Crystals sometimes glassy at centre. 
Analyses of specimens from iron-furnaces: 1, 2, by A. Knop, differ- 
ent specimens of same slag from the Hartz; 3, Dr. Limpricht, another 
' slag from the Hartz; 4, Knop, from Neuwerk, of the Brunswick Hartz : 
1. 
Silica, ; 557 59°45 5427 55-41 
Alumina, 15°28 15°43 9°40 1152 
Lime, _ ; 29-21 2512 ee 80 8 10 
Magnesia, : 7 ._— 
Protox, iron, . : 100-27 —— =100 é sar007 $08 
Analyses 2, 3, and ri give for the ony gen ratio of R, 8 5i, 
2, 718: 721: 3150 =1: 31 4 (nearly). 
3, 10-29 : 4:39 : 28°75 = 2°34:1:655 
4, 9-47 : 5°38: ridiegens ta: 1: 5-43 
These ratios afford for the oxygen of all the bases and the silica the _ 
ratio nearly of 1 : 2, which is characteristic of both pyroxene and beryl ; 
apt e: deduces the formula Ga? Sit+ A1Si?, and points out the 
close ssecalarity, to beryl, if glucina be taken as a protoxyd, the difference 
