170 BULLETIN OF THE 
gravity of fragments, determined by Westphal balance and Thoulet 
solution, was between 2.570 and 2.572. 
The following analyses of the feldspar (I.) and the rock (II.) were 
made in the laboratory of the U.S. Geological Survey at Washington 
by Dr. Thomas Chatard. 
Jt ile 
Feldspar. Keratophyre. 
50 at OMG Y &er. .04 al 
H,O at red heat. . . 37 1.28 
IS sh 4., s 2 a bs ee eOOLOO 70.23 
SPIO F230 PNA ly ORME USS 03 4 
Se array ey eereeerct. 7 .06 
tO aes! Pan 0 eee 2 15.00 
ETOr 2S eee VS 7 came CEAEeS 1299 
FeO er) viene) “traces 
I) 70 ae RA end aS 13 24 
CAO’. 28a? > Sa -67 33 
MaOuie da shaeaighol were 38 
K,O So ae GOS 4,99 
NaiG)) Ma titionp BylangIgG 4.98 
III. IV. 
Gmelin, No. 1. No. 2. 
SiO; cece ae ia) 4 eee Loo 65.19 
BLO), an ole eee go ee © 19.99 
HCO) Ue chee ame ee 63 
CaO SRO COST ec .28 48 
MgO ‘ 
K,O Seta duet ac RS AOD 7.03 
NSO a Ges gen ie gd ee OL 7.08 
[eB RRS Seton ‘ 12 .o4 
Specific gravity 2.587. 
It is evident from the analysis and optical properties that this is a 
triclinic soda-potash feldspar of remarkable purity, and very evenly 
balanced percentages of Na and K, belonging to the anorthoclase group 
of Rosenbusch. For comparison, analyses (III. and IV.) by Gmelin 
are appended of anorthoclase from the augite syenite of Norway (Brog- 
* The TiO, was not very pure, and its presence is not absolutely certain. 
