S. P. Sharples on Minerals from Chester Co., Pa. 319 
Art. XX VII —Contributions from the Laboratory of the 
Lawrence Scientijic School. No. 7.—On some Minerals from 
Newlin Township, Chester Co., Penn., described by Dr. Isaac 
Lea; by 8. P. SHarpres, 8.B., Assistant in Chemistry. 
gave me several minerals for examination which ha 
scribed by Dr. Lea in a paper read before the Academy of Nat- 
ural Sciences of Philadelphia, April 9th, 1867. : 
e first of these that I examined was the Diaspore which 
Prof. Brush described in this Journal and of which an analysis 
18 given on page 169, of Dana’s Mineralogy. The diaspore 
was embedded in a mineral which Prof. Dana calls margarite 
(loc. cit.), and which Dr, Lea in his paper spoke of as emerylite. 
I found it to contain silica, alumina, potassa and water, with 
traces of iron, magnesia and soda in the following proportions: 
A YEAR or two ago, Wm. W. Jefferis, of WestChester, Penn., 
e 
1. z, os 4. 5. Mean. Oxygen. 
Si0, mig “GCE? ee, ae 
Al,0, pga eee SIG 11416 
H,0 iS Bg ig ee Be OI 
K,0 re ae ee eee 
Sp gr. 2°87. 
The oxygen ratio as will be seen, is for R, #, Si, H, 1:8'5:11: 2, 
which corresponds with that given for damourite. e 
The mineral occurs in mica-like crystals, some of which are 
Mm one to two inches across. Some of the specimens in Dr. 
Lea’s collection have well crystallized edges. In color it varies 
trom white to greenish or yellowish. Before the blowpipe it 
fuses with extreme difficulty to a white enamel. 
: Lesleyite—This mineral is described by Dr. Lea as follows : 
‘Fibrous or lamellar, sometimes inclining to massive. Color 
Whitish passing into reddish. Hardness about three. Streak 
white. Before the blowpipe it parts with its water and becomes 
Opaque white. Does not fuse with borax. Does not dissolve 
in muriatic acid, Under the microscope it presents no observ- 
able characteristics. voor 
“Tts gravity is greater than that of quartz, There is a dis- 
Position in the crystalline fibrous structure to diverge from a 
Central point, to be stellate, and in one crystal before me, the 
tadiating fibers are nearly four inches long.” | é 
Analysis of the white variety gave me silica, alumina, po- 
tassa and water with traces of iron, soda, lithia and magnesia. 
