16 TRANSACTIONS OF THE [ocr. 19, 
_ in the slide, it is shown by the loss to have suffered some alteration. 
No. 102, taken from the Vermont report, p. 585, is the cementing 
magma of a breccia dike to be later described. No. 11 is abnormal 
and is of the coarsely crystalline dike of Shelburne Point, referred 
to above. 
No. 66, No. 11, No. 102, 
Kemp, 3. Morrison, 2. G. F. Barker. 
Loss . . . . » 4.30 6.57 1.70 
SiO, ‘ : : - - 62.28 53.40 67.30 
Al,03 ; . : 5 4 ile)eily/ 20.82 
| We ibe I tape wbiogad 3.92 } sn 
CaO : : : : Page le: 7.05 0.79 
MgO - - : . - trace 1.53 trace 
K,O : 5 - 5 5 Be Ae 2.97 4.74 
Na,O - “ 5 ° . 5.374 3.79 6.04 
SBieg il 100.05 99.67 
Sp. gr. 2.648. 
No. 11 was kindly analyzed by Mr. W. M. Morrison, resident 
graduate in chemistry at Cornell University. The amount of soda 
in No. 66 is very suggestive. As no w ell-marked plagioclase 
appears in the slide, which is of a very homogeneous rock, the infer- 
ence is strong that some soda orthoclase (anorthoclase) is present 
and that the dike is really allied to the keratophyrs and pantellerites. 
Years ago (1853-56) T. Sterry Hunt separated a number of feldspar 
crystals from related dikes in the region of Montreal, and, as shown 
by the accompanying analyses (I-IV inclusive), they furnish close 
parallels. V and VI are analyses by Forstner of the anorthoclase 
of the trachytic rocks of the island of Pantellera, and their simi- 
larity with the older analyses of Hunt is very striking. Analysis 
VII, by T. M. Chatard, of the keratophyr described by J. H. Sears, 
from Marblehead Neck, is wonderfully like the others. The kerato- 
phyr described by W. S. Bayley, from Pigeon Pt., Minn., is much 
higher in silica (A. J. S., iii, xxxvii, 54). 
Te II. 100G IV. V. WA VII. 
SiO, 65510 65.15). 66.15 (67260) 66:06 166.03" 65.66 
Al,O, 20.80)" 20555759 A975" 18-30) 19-2475 1937 eee 
FeO _— — — —_ 0.54 — trace 
Fe,0, — — —_ 1.40 — 1.53 trace 
MnO — — — — — — 0.13 
CaO 0.84 0.72 0.95 0.45 eat 0.73 0.67 
MgO = — os _ 0.11 0.02 0.18 
K,O 6.43 6.32 7.53 5.10 5.45 5.40 6.98 
Na,O 6.52 6.67 5.19 5.85 7.63 7.57 6.56 
Loss 0.50 0.50 0.55 0.25 none none 0.41 
100.79 99.99 100.12 98.95 100.14 100.65 100.64 
I, T.S. Hunt, Feldspar from Brome (Canada), Trachyte, A. J.S., ii, xxxviii, 
97; Geol. Canada, 1853-56. 
II. st Feldspar from Shefford, Canada, l.c., p. 97. F.D. Adams has 
described a rock from Shefford as quartz-free porphyry, 
Geol. Canada, 1880, ’81, ’82, p. 10a. 
