177 
ROSiO, + 2(R,0,810;) + kKHO 
being known as Margarodite. 
«<The Micas of the Dublin, Wicklow, and Carlow granites, 
analyzed by me, belong to the Margarodite genus, and contain 
two atoms of water, corresponding to k = 2. 
“The following are the analyses of three micas selected 
from three distant localities of the granite chain of the south- 
east of Ireland. 
‘¢ No. 1. Mica from the Three-Rock Mountain, county 
of Dublin; gray, transparent, containing specks or flakes of 
a bronze-coloured or black mica. 
Per Cent. Atomic Quotients. 
Silica: .. apematiiewss. 0959) -iaea.. 286Se.... 3 
Abomina,-, . sae. .. 0611 : 
: 0670 ~ 2000 . . 2 
Peroxide ofiron, 4°79 . . 0:059 7 
Rime yo. a SS? --  O'0495 
Magnesia, . . 113 . . 0:056 | 
0:3 ATEN ea Ghee 
Rotashs., ... . | KOYE, . . 22s | 2 
eae. | RD... O'O4AG 
Loss by ignition, 543 . . 0603 ... 1800 .. 2 
99°77 
«No. 2. Mica from Glendalough valley, county of Wick- 
low, gray, transparent, with specific gravity = 2°793. 
Per Cent. Atomic Quotients. 
See se AA TOY GSR TIA SEP HI DOLL an 3 
“omnes, . . b113'' 5) 0606 
Peroxideofiron, 469 . . 0:058 LAL SR SNM cai 
ime, . . 9. 1:09. . 0:035 
Magnesia, - . 090 . . 0.045 
Potash c OO... = cOQ1) a sic Malady 
Ge Pe oc) 2g 8, sO OFT 
Hoss by ignition, 622 . - O691 . . . 2083 . 9. 2 
99°92 
‘No. 3. Mica from Mount Leinster, county of Carlow, 
gray, transparent. 
