820 S. P. Sharples on Minerals from Chester Co., Pa. 
+: 2; 5; 4, Mean, Oxygen. 
sid, 33°63 33°54 aoe Bets 33°59 16°88 
Al,O, 5538 55°45 wees oe 5541 25'82 
Balt Sh aS OG 7:30 7-57 7°43 1:27 
H,0O 4°31 4:29 ce earns 4°30 3°82 
Sp. gr. 3'203 
Oxygen ratio for R, #, Si, Bets 3014; 3, 
The reddish gave C, W. Reepper of Bethlehem, Penn.: 
2. 3 
1. Mean. Oxygen. 
Sid, 4714 46°87 nee 47-00 25°06 
Al,O, 33°56 32:98 ct 33°27 15°50 
Fe,0, . 2:75 2°93 re 2-84 85 
Wits alk 9-97* erie 1°69 
H,O 73 67 aud 6-71 5:97 
water containing alkaline silicates upon the corundum, and are 
i, H, 3: . 
white variety the ratio is 7:5: 1, while the reddish gives 3:4:1. 
attersonite.—Of this mineral Dr, Lea says: ‘ Basal cleav- 
age imperfect, rarely if ever presenting a hexagonal prism, 
but disposed to present triangular plates which joining make @ 
sub-tetrahedral mass, The laminw are not flexible and but 
slightly translucent. The color is metallic bluish gray, resem- 
bling zinc. The streak is grayish. Before the blowpipe parts 
with its water but does not exfoliate nor intumesce. With 
rax gives a black bead.” I found it to contain silica, iro, 
lumina, magnesia, potassa and water, with traces of soda and 
lithia, The potassa was determined by difference owing to the 
very small amount of the mineral at my command. 
i 2 Mean. Oxygen. 
=e 30-20 ee 30-20 1611 
Sas 14-88 See 14°88 04 
ave 2048 2061 20°55 = 
nH 119 1:38 1-28 a 
20 — 8 11°35 
H,0 1180 ~—:11-66 11-73 10°48 
Ratio for &, ® SH, 1:5°7:66:43; for (t ®, $i, H, 3:3:2 
* Sharples. 
