24 Clarke and Chatard—Mineralogical Notes. 
8. PROCHLORITE. 
A dark-green chlorite collected by Mr. G. P. Merrill on 
Foundry Run, Georgetown, D. C., may be assigned to the 
above-named species. The mineral is very dark in color, 
sealy-crystalline, and — in quite fine specimens. 
Analysis, F. W. Cla 
RON et a eee ae 14°43 
PE ee hoe eae 25°45 
TRO a ate. 15°04 
OR UNINS a ns a ees Sets 17°88 
A Sieg OSUNO a So gan. 26°08 
Me ok tee oko Eo owns 67 
98°45 
The iron was all reckoned as ferrous iron, although a little 
of it is probably ferric. 
9. HALOTRICHITE. 
was 
were aay | soluble in water. e calves (Clarke) gave 
results which place the mineral under or near halotrichite. 
WORGEE ee 40°62 
Sulphuric acid (SO,), .-.------ 37°19 
HOMHOS ORING. oi ocd aee se 13°59 
Ainge fo es ‘ 
POSING Foe ey, 0°50 
99°17 
A very little of the iron, but not enough to estimate, was in 
the ferric state. The mineral is reported to be abundant. 
10. ALUNOGEN. 
Associated with the halotrichite at the foregoing locality are 
great quantities of alunogen. The specimens received at this 
laboratory were crusts of various colors, white, pinkish, yel- 
lowish, brown and drab. Most of them contained sulphates of 
iron in small quantities; but one sample of sie color, was 
free from such ogy Sea ‘ 
Analysis, F. W. Clarke. 
