164 BULLETIN OF THE 



quartz, ilmenite, muscovite, etc., may indicate a higher degree of meta- 

 morphism than those minerals alone would do, or the presence of some 

 special geological or chemical conditions, to which we have as yet 

 no clue. 



Graphite Schist with Ilmenite Plates. — This rock occurs as a boulder 

 on Miantonomah Hill, Newport, R. I., and contains plant impressions 

 (Dale). 



It is a soft black graphite schist, containing irregular metallic plates 

 resembling ottrelite, which are two or three millimeters long and 

 0.12 mm. thick. These plates can easily be split off with a knife, 

 leaving a dull film of chlorite below them. They are imperceptibly 

 magnetic, are attacked with great difficulty by boiling hydrocliloric 

 acid, and the yellow solution gives a strong titanium test with tin-foil ; 

 they are therefore ilmenite. In the slides the rock is composed of small 

 grains of quartz, flakes of muscovite and chlorite, and specks of graphite 

 and iron ore (probably ilmenite). The large ilmenite plates have 

 frequently a spindle-shaped cross-section (i. e. discoid plates), and have 

 a kernel of leucoxene (titanite). Some are bordered on each side by a 

 thin plate of chlorite, some by brilliantly polarizing muscovite. The 

 rock is evidently of Carboniferous age. 



Occurrences of minerals of the ottrelite group in the region of schists 

 and gneisses of Central and Western Massachusetts are mentioned in 

 mineralogies, but the writer has found no microscopical descriptions 

 of the rocks. A part of the so called ottrelite schists, such as the 

 " spangled mica-slate " of Hitchcock (Geology of Massachusetts) are 

 probably ilmenite schists. 



In the Western or Green Mountain region, ottrelite and ilmenite 

 plates occur in schists or phyllites investigated by the writer for the 

 U. S. Geological Survey, both in specimens collected by Mr. T. N. Dale 

 from the Western Cambrian (or younger) rocks (Taconic region), and 

 also from the Cambrian series of Hoosac Mountain in the axis of the 

 Green Mountains, full descriptions of which will appear in the forth- 

 coming memoir. 



The ottrelite schist of Hoosac Mountain occurs in several places in 

 the albite-phyllite series which overlies the basal Cambrian conglom- 

 erate. The ottrelite rock is a silvery greenish schist, containing crys- 

 tals of red garnet and small prisms of tourmaline, and spotted with 

 plates of ottrelite. In the slides the rock is composed of muscovite 



