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On Rutile and Chlorite in Quartz. 351 
the color is proper to the quartz, or occasioned by the reflection 
from the rutile crystals. Mr. Alger finds almost no rutile in the 
white quartz crystals from Waterbury, “ while the colored varieties 
abound with it,” and probably, he suggests, owe their color to it. 
The rutile crystals are from the size of the finest hair and al- 
Most invisible, up to a twelfth of an inch in diaméter and five 
inches long; they are uniformly distributed through ‘the quartz, 
and intersect and cross each other in all directions. ‘There is no 
radiation from a centre, but in many instances the crystals have 
one or more large graceful curves, and sometimes two in opposite 
directions, and some are bent at an angle either right or oblique. 
any are broken at the surface of the quartz, while others are 
Wholly included in it, terminating in a single plane or tapering 
to a point. 
They are all of a uniform bright reddish brown color, and of |» 
the lustre of polished copper. Where the ends are seen on the 
polished faces they have the color and lustre of polished steel. 
nN humerous cases the surface of the crystals is covered here 
and there with a brilliant, silver white mineral, sometimes limited — 
to the lateral edges, and again investing parts of the prism at in- 
tervals, or with frequent ‘interruptions, giving it the appearance of 
eing made up of numerous short white and brown prisms, the 
orm remaining unchanged. In some éases this mineral occurs 
like a thin disk, through the centre of which the rutile appears 
to penetrate. I have not been able to determine with certainty 
the nature of pa _and can only conjecture that it is the 
same with the cufyed crystals described below. 
In the writer’s specimen, a8in those described by Mr. Alger, there 
are humerous vermiform, tortuous and convoluted crystals. By 
transmitted light, theyare sometimes of the color of copper, thought 
faintly so, or,of a bronze yellow, or of greenish and yellow shades 
oreven very dark, and by direct light they are almost'black.’ These 
ir nsversely finely striated, — 
crystals are regular hexagonal prisms, tra 
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and appear to be made up of thin plates of slightly varying size, 
8iving thé érystals a varying diameter. They occur either singly 
or in groups of several laterally joined, and united in all their 
convolntions, and having a single terminal plane, highly lustrous, 
which often presents a silver white color. ‘The above figures, en- 
