C. M. Wetherill on Itacolumite. 63 
also by attacking another portion of mineral by hydrofluoric acid, 
was 2:03 p. c. he iron is not distributed very uniformly 
through the rock, as may be readily seen by an inspection of 
specimens. 
I found it impossible to separate completely the mica from 
the quartz by edulcoration. When the result of the washing 
is examined with the microscope, scales of mica are seen, gene- 
rally colorless, but sometimes dark brown, and all polarizing 
light, as do also the grains of quartz. 
This fine edulcorate when heated on platinum foil B.B. cakes 
together slightly, and a slight dust adhering to the platinum 
does not fairly melt but exhibits signs of intumescence. ith 
salt of phosphorus very fine grains of silica are seen floating in 
the bead. ith borax aclear glass without intumescence re- 
sults. An experiment for HF! with the itacolumite mica yield- 
ing negative results. 
e mica examined with the spectroscope gave the reactions 
of KO and NaO only. No different result was obtained after 
the mineral had been attacked by liquid hydrofluoric acid, and © 
the residue evaporated to dryness with sulphuric acid before ex- 
posure to the flame. 
The relative hardness of the siliceous grains in the mineral 
appears to be that of agate which may be scratched slightly by 
them. On one occasion the bottom of an agate mortar receive: 
a very decided scratch which gave color to the supposition of a 
Minute diamond as the cause. The rock is quite porous when 
compared with other sandstones; water placed in an excavation 
will filter very readily through the stone, even in a direction 
cust to the plane of stratification. Gases di use very 
‘asily through these pores; if a slab of the itacolumite one 
quarter of an inch in thickness, be cemented to the top of a 
glass cylinder, which is then filled with hydrogen, water rises 
— rapidly into the tube. 
