ON THE CRYSTALLINE ROCKS OF ANGLESEY. 319 
No. 1124. 
17 S.W. Porth Nobla. SS. Side. 
I, I. Til. IV. 
Si, : - : . 70°37 70°33 
Al,O, : 5 Fate 14:95 
HeOy. . 2 : . 0:34 0-71 
FeO d : ¢ . 424 4°32 412 4°58 
CaO ‘ - - ae elS 1:26 
MgO A : ge a1s93 _ 1:84: 
K,O : ‘ ; ee a20 2°34 2-01 
Na,O eo 2°96 2:53 
H,O (Hygroscopic) 5 US 0:13 
H,O (combined) . . 1:03 1:08 
99°84 99-92 
Nos. 18a and 2144 are banded, highly crystalline rocks, which occur 
' within the zone of hornfels, but are much coarser and more saccharoid, 
and this parallel structure a banding rather than a foliation. 
perhaps be called phenero-crystalline hornfels. 
In 18a the dominant mineral is muscovite ; in 2144 a pale hornblende. 
In 18a tourmaline is an abundant accessory. 
No, 18a. 
12.8.2. South of Holyhead Road near BM, 96:5. 
They may 
L. IL. it. 
SiO, : ¢ S . 62°91 63°49 63°53 
TiO, ; s . : 053 
Ep ed OS eee 25-97 25°57 
ee. 5 | ee eae ee 
FeO ‘ ; ' . 447 Al,O; + Fe,Q,, including FeO 
CaO : F A sh Le4T 1:80 1:31 
Wee os seg ad 2:32 248 
fete st. ae Oe 
NazO. : : . 299 
co, . O19 : 
H.0 (hygroscopic) . » Oral d 0:28 
H,O (combined) . i 83 : : 1-78 
100°53 
Analyses IT. and III. above, of SiO,, Al,O,+Fe,0,, CaO and MgO, 
are by Miss C. Pearson, B.Sc., and the second determination of H,O 
(hygroscopic and combined) by Mr. R. W. Everett. : 
No. 214a, 
13 NW. 600 feet N.W. ‘MW? of Maengryn. 
It, Il. 
i kh a ak oe GEBY FTA 60°33 
Al,O, ; : - 5 lireika) 16°51 
HesOn « : e Sus é : 1:20 
FeO . Z ci tae eatets) ; 5 4°81 
MnO : : 5 . traces 
CaO - F 5 oor Orel 5:25 
MgO 3 - a 5. 288 2°65 
K,0 6 : 3 » 3°59 3°80 
Na,O E xe 3 OF 3°85 
HO (at1l0°). . . 0-13 0-17 
H,O (above 110°) . . 0-95 1-03 
99-64 99°60 
