162 BULLETIN OF THE 
panies the quartz in the ottrelite, but buts against the edge of the 
crystal without altering its character or arrangement in proximity to it. 
Sometimes the quartz grains fill the interior of the ottrelite in hour-glass 
shape, but this form has no connection with twinning as in the case fig- 
ured by Rosenbusch (Mik. Physiog., Vol. I. Plate XXII. Fig. 6), but is 
evidently a case of crystal growth analogous to the forms so well known 
in the augites of some eruptive rocks: a skeleton crystal of ottrelite 
first formed, which did not enclose or else assimilated the quartz, while 
a later growth, which filled out the double funnel-shaped cavity, was 
able or obliged to enclose it. In the rock next to be described there 
are skeleton crystals of ottrelite only partially filled up with the quartz- 
bearing mineral. 
The black plates in this rock are somewhat smaller than those of 
ottrelite, with a jagged outline. They have sometimes a spindle-shaped 
cross-section, indicating then that they are discoid, but are generally 
bounded by straight parallel lines; they are not transparent, but have 
frequently a yellow leucoxene core, indicating titaniferous iron ore. 
There is no doubt that they are ilmenite, as determined by M. Renard 
in the similar rocks of the Ardennes.? 
These ilmenite plates are generally bordered on both sides by a thin 
sheet of chlorite, the base of which is parallel to the ilmenite. (The 
similar ilmenite plates described by M. Renard are bordered by sericite.) 
The plates are often entirely enclosed in the ottrelite crystals, some- 
times one half in, the other half projecting out. The chlorite coating 
disappears when they are found in the ottrelite, but they are then some- 
times bordered by a zone of ottrelite free from quartz inclusions, unlike 
the rest of the crystal, of the same size and shape as the chlorite, sug- 
gesting that the latter was absorbed into the ottrelite when the crystalli- 
zation took place. Small grains of titanite mixed with black ore are 
scattered through the rock, and there are occasional prisms of tour- 
maline. ; 
Ottrelite Grauwacke. —This interesting rock was found by Mr. Dale in 
a glacial boulder at “ Paradise,” Newport, R. I. 
The rock contains fragments of blue and white quartz, enclosed in a 
dark gray micaceous cement, spangled with small plates of ottrelite. 
The slides show that the rock has undergone intense dynamo- 
metamorphic action; the large fragments of clastic quartz in polarized 
light exhibit all stages of change from mere straining to breaking and 
1 He mentions the occurrence of these forms in Rhode Island ottrelite schist. 
