TRANS. OP TJIB ACAD. OP SCIENCE. 
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114 
^ Topaz in Utah . By Henry Engelmaot. 
Curing my explorations in Utah as Geologist of the Expe- 
' j dition under Capt. J. H. Simpson, Top. Eng’rs. U. S. A., in 
1858 and 1859, 1 observed some remarkably beautiful crys- 
tals of Topaz among some detritus of trachytic porphyry, 
t They were perfectly colorless, transparent, sharply devel- 
X oped, and of great lustre. They were all short columnar. 
X lail gest 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 
s 'according to Prof. Rose’s designation) 
d c : b : a r go c : b : 2 a , c : oo b : : *oo a 1 , 
4 c : b : qo a , 2 c : b : a ; 
nost of them also 2 c : b : oo a , ' ; b : a ; 
- few only 2 c : op'b : a , and 4 (?) c : b : a . 
As in none of the crystals were both ends developed, I 
ould not ascertain whether they were liemihedral, 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 
silex. No tests were made for other elements, nor were the 
^ y T e/t^i^d life |^ol a rlza- ^ 
The local ity^of the mineral is near lift. 89° 40', long. 113? ; 
'30'^est of^feen wich;' west of. south of Salt Lake,' in Thon\- ' ^ 
as’ range ofmountains, on Capt. Simpson’s return trail. Cir- 
cumstances prevented me from obtaining more than a few 
cry stals r which are now deposited in the collection of the 
Smithsonian Institute ; a few others are also in the tianjjs -of 
members of the party. We were travelling at the time by 
forced night marches with nearly worn out animals^ seeing 
to gain a spfihg pf water in a distant range of mountains. 
This desert wa^^en entirely unexplored. I have but little 
doubt that more mteresting materials are to be found at the 
same point. 
The mountains of the former Territory of Utah promisj^a 
rich yield to the mineralogist. We know already of gold and 
silver ores in the east, west and south part of that*district ; 
of copper and lead ores in 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 Ljttle S'aft 
Lake ; of rock salt in the mountains south-east of Ujfcah Lake; 
of native alum near Salt Lake; of various other salts inihe 
deserts ; and of silicates, composing the granites, pbrphyiaes, 
diorites, trachytes, and lavas, nearly over the whole area!** 
Missouri »Bot*nic 
George Engeuma 
ARDCTT 
\PER5 ' 
• . . • Botanical 
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