114 TRANS. OF THE ACAD. OF SCTENCE. 
Topaz in Utah. By Henry EncetmMann. 
During my explora tions in Utah as Geologist of the Expe- 
dition under ‘apt. J. i. Simpson, Top. Ene’rs, UlS. A. 
1858 and 1859, I observed some remarkably beautiful e Crys- 
tals of Topaz among some detritus of trachyti tic porphyry. 
They were perfectly colorless, transparent, sharply devel- 
oped, and of great lustre. They were all short columnar. 
The largest of them measured scarcely one third of an inch 
in the direction of the basal cleavage, which was highly per- 
fect. I observed ten modifications: all crystals exhibited 
(according to Prof, Rose’s designation) 
Oe. 0 a yO Gt Ea et wt te a 7 
Aol bs ea, Bo 0k: 
most of them also 2 ¢: bi oa, G2 ble | 
atew only = A €coobti a, and 40) ¢ i be a . 
As im none of the crystals were both ends developed, I 
could not ascertain whether they were hemihedral, as is most 
common with topaz. The hardness of the mineral is —8. It 
is Infusible before the blowpipe; and when strongly heated 
is coated with small blisters, but does not show any change 
of color. It exhibits the reactions of fluorine, alumina, and 
siex. No tests were made for other elements, nor were the 
erystals cXamined in regard to pyro o-electricity and polariza- 
tion of light. They exhibit double refraction quite plainly. 
The locality of the mineral is near lat. 89° 40, long. 113° 
3 west of Greenwich, west of south of Salt Lake, in ‘Thom- 
as’ range of mountains, on Capt. Simpson’s return trail, Cir- 
cumstances prevented me from obtaining more than a few 
crystals, which are now deposited in the collection of the 
Smithsonian Institute; a few others are also in the“hands of 
members ef the ae We were travelling at the time by 
forced wight marches with nearly worn out animals, seeking 
to gain a spring of water Ina distant range of mountains. 
This desert was then entirely unexplored. ‘Thave but little 
doubt that more interesting materials are to be found at the 
same point, 
The mountains of the former Poy of Utah pre omise a 
rich yield to the mineralogist. We know already of cold and 
silver ores in the east, west and south part of that district: 
ef copper and lead ores im the south, and I have discovered 
the latter also in the centre of it; of specular iron ores and 
native sulphur in the Rocky Mountains and near Little S; alt 
Lake; of rock salt in the mountains south-east of Utah Lake; 
of native alum near Salt Lake; of various other salts in the 
deserts ; and of silicates, composing the granites, porphyries, 
diorites, trachytes, and lavas, nearly over the whole area. 
ae 
