MUSEUM OF COMPARATIVE ZOOLOGY. 165 
(sericite) in the usual interwoven aggregates, irregular plates of chlo- 
rite, grains of quartz, occasional crystals of albite and the ottrelite, in 
small irregular plates with the usual pleochroism, etc., which sometimes 
appear spindle-shaped in cross-section (discoid). Small, irregular ‘black 
metallic plates also occur in the rock. 
The Taconic region of Greylock Mountain, the highest summit in 
Massachusetts, lies immediately west of the Hoosac series, extending 
west in turn to the Taconic range, which forms the boundary between 
New York and Massachusetts. The rocks of this area are in large 
part phyllites of many varieties and colors, often dotted with crystals 
of albite like the similar rock of Hoosac Mountain, containing garnets, 
tourmaline, etc. The black metallic plates are wide-spread in these 
phyllites, exhibit the same properties, such as very feeble magnetism, 
difficult solubility in hydrochloric acid, presence of titanium, etc., that 
those from the Rhode Island graphite schists do; they are therefore 
almenite. 
In the slides these rocks are composed of sericite, generally intimately 
interwoven with chlorite, and small grains of quartz. Masses of black 
ore, prisms of rutile, etc., are abundant. In some varieties the albitic 
feldspar becomes an essential constituent. The ilmenite plates are 
commonly sandwiched between two plates of dark green chlorite, exactly 
as in the Rhode Island rocks. In many of these rocks microscopic 
plates of ottrelite, spindle-shaped in cross-section, exist enclosed in the 
meshes of the mica. 
April, 1890. 
