22 TRANSACTIONS OF THE [ocr. 19, 
I. ite Ill. We Vis VI. 
SO, 5 - 43.50 41.00 41.94 40.95 48.19 44.87 
AlTOn te : oe 7.02) (2136) lb 66 G45 Gao) seas 
HeiOn yaw ai. oe (1BG8. BAe ROT 5.47 Seay ee 
BeQi eres w tien) Pie = DA ay che 
NnOnsy. 4 ea — 0.25 0.33 — trace. 
NOS CONE | Aah = 2 AG) 1 Or9a ee 6.74 
CaO Ho) se, SAS: (10.40. 9:47. 100535 66S ee 
MeO us gael <n 62840 B05) * LOI #, 6.10" Aaa eee 
K,O gas S02 ST! OH) p08 Loe set anes 
Na,O yr nh “DRB4 OVE 5157) 400 = 5 50. eee 
PO ee ser ye eee = = oe 0.45 
CO,e ee wag ME) ee a 
LOSS fos idhoprs ga re BBE of OBGO0) hs ake BA ee ade eee 
Total 5 - 99.40 99.22 100.44 100.63 100.53 99.59 
I. Fairhaven, Vt. By J. a ie Amer. Geologist, Aug. 1889, p. 97. 
II. Proctor, Vt. do. “do. 
Ill. Campton pee Na He @ Ww. Hawes, Amer. Journ. Sci., iii, xvii, 14. 
IV. Montreal. B. J. Harrington, Geol. Survey of Canada, 1877-78, p. 439. 
V. Forest of Dean, Orange Co., N. Y. J. F. Kemp, Amer. Journ. Sci., April, 
1888, p. 331. 
VI. Fort Montgomery, Orange Co., N. Y. By L. M. Dennis for J. F. Kemp, 
Amer. Naturalist, Aug. 1888, p. 694. 
The Monchiquites. 
The name monchiquite has been lately introduced by Rosenbusch' 
to include a group of dike rocks consisting of olivine, augite, horn- 
blende, biotite (one or all three of the last named), and a glassy 
base. It is derived from the Monchique Mts. in Portugal, where 
such dikes were discovered in 1850. In the further development of 
the Lake Champlain dikes toward the extreme basic end of the 
series there are a number consisting chiefly of zonal augite, small 
brown hornblende and biotite crystals, and olivine, in an unresoly- 
able base that is only very feebly refractive, if not actually glassy. 
Yet some slides do show minute plagioclase crystals in the ground 
mass, but not in sufficient development to throw them into the camp- 
tonites. Magnetite is the only additional mineral. The augite is 
the same as that described under the camptonites, and is in two 
generations. It makes up at times almost if not quite the entire rock 
and the analysis (No. 14) given below must indicate the approxi- 
mate composition of this mineral. Magnetite is the only other com- 
ponent of note. The hornblende is also like that of the campton- 
ites, but when the second generation becomes very small it is very 
difficult to distinguish it from biotite. In the altered portions of the 
base they seem much more abundant than in the fresh, as they 
stand out with very sharp definition. The alteration-product is 
calcite. The hornblende in one or two instances replaces the augite 
1M. Hunter and H. Rosenbusch, Ueber Monchiquit, ein Camptonitisches 
Ganggestein, etc., Tsch. Min. u. Petrog. Mitth., xi, 1891, p. 445. 
