J. Lawrence Smith on Emery. 57 
authorizes one to suppose that they are represented by the crys- 
tallographic signs g* and ¢%. The faces M and those of the sum- 
mit have a very bright lustre. ‘The primitive form of the dias- 
pore is undoubtedly a right rhombic prism of 130° 2’; the fact 
that the base is horizontal, is shown by the identity of the angles 
of the faces b' on the anterior faces M, and the faces b' on the 
posterior faces of the same. This position is verified in seeking 
Diaspore of |Diaspore of { Diaspore of Gumuch- Hydrated Oxyd 
St. Gothard, [Schemnitz, dagh near Ephesus, _|of Iron, of Corn- 
MM welncnn i: } Marignec. | nger. Dufrenoy.* _ wall, Dufrenoy. 
ORO ee 130° | 129° 54’ Ts0° 2” ss 
18 a Sd ae idee iedeletld bs car a ae (ASO? 17! 
M: (posterior faces), | ......00. |e-ee+ oe 125° 18’ 
BR etc, 118 Lg ies 114° 58’ 
bi 5 Re a ee 1049 To 9 104° 
bt ths ft pate CESS 151° 86’ | 151° 36’ 151° 85’ 
Bi Ta (Posterior faces), |... .......Jepeeeers 151° 33’ 151° 34’ 
1: 2, OPPOBite faces),| 116° 38’ |........ 116° 18” ie 
te |, Oe eae fos ce 67° 6’ 
fa: aaee Precis cae; 144° 40! |oe.eeees 
Vike Sooo 14S 40 lis scaned 
gl oF eo 7 Bee ie ek ee TEG2 1 ht eee ws eee ees eee 126° 20’ 
a eS 118° BGs. 2550 |e ee eee es 116° 55’ 
LR eS ct | 1a) meetpreeated Reger PoE, 117° 10’ 
SS ES a Jeetersesestertes | 
Thave found crystals of diaspore in hydrated oxyd of iron, the 
n . - 
eedles traversing the oxyd in_all directions. There 1s p spect- 
n 
ie Summits of the crystal is exposed. In breaking the oxyd of 
pa hich contains these crystals, they become detached, leaving 
€ oxyd an impression with a very brilliant surface. 
ake 
oe 
* oS a 
oa values of shew angles are just as given by the goniometer without any ecor- 
Vol. XI, No, 31.—Jan., 1851. 8 
2 
