264 J^t"^ A/nerica/i Geologist. Novembor, igno 
Schrauf,*in 1869, made a very careful and detailed study of 
the inclusions in labradorite from the coast of Labrador and 
from several points in Russia and distinguished: 
thirst, Augite needles, usually numerous. 
Second, "Microplakites," of unknown nature; they are 
I^erpendicular to the augite needles; usually square v^^ith 
sharply defined outlines; they are reddish, greenish or bluish 
in reflected light, and brownish in transmitted light; being- 
dark between crossed nicols, but perhaps not monorefringent. 
Third, "Microphyllites," of unknown nature; they lie par- 
allel to the augite needles; and are roughly oblong without 
good outlines; they are gray brown, and monorefringent; and 
lie in the cleavage plane (180). 
Hagge, f in 1871, studying rock from Labrador again, 
found that all the brown scales were dissolved in hydrochloric 
acid. before the feldspar was attacked at all, and concluded that 
they were gothite. 
Judd,;J;on the contrary, found that those in the gabbros of 
Scotland were insoluble in hydrochloric acid. He considered 
that the inclusions arc composed of various hydrous oxides, 
such as opal, hyalite, limonite, gothite, and also "titanoferrite" 
and are not definite chemical compounds, but amorphous mix- 
tures, and hence anisotropic. He asserted that they are all 01 
secondary origin, due to the solvent action of water at great 
depths and under high pressure; in such circumstances the 
?;<.)lvent power of the water is greatly increased and it acts 
along certain planes of strain ; the inclusions are evidently not 
derived from the labradorite, but according to Judd from the 
accompanying augite. Tn short he considered them schilleri- 
zation products. 
"Adams § found similar inclusions in labradorite from Can- 
*Schrauf: Studien an der Mineralspecies: Labradorit: Sitzber. 
Akad. Wissensch^ Wien. Bd. LX. (i) p. 996, Dec. 1869. 
tHagge: Mikroskopische Untersuchnng iiber Gabbro und ver- 
wandte Gesteine . Kiel. 1871. p. 46. Cf. Adams: Neucs Jahrb. f. 
-Mineral., etc. Bd. VTIl. p. 436. 
JJudd: On the gabbros, dolerites, and basalts of Tcritary age in 
Scotland and Irelanfl; Quart. Jour. Geol. Soc. 18S6. Cf. Judd. Quart. 
Jour. Geol. Soc. 1895. p. 354. 
§F. D. Adams: Ueber das Norian oder Ober-Laurentian: Neues 
Jahrb. f. Atiner., etc. Bd. VIII. 1S93. p. 435. 
