290 Haworth on the Aj'chcean Geology 0/ Missouri. 
New England granites which are found in the market. Mus- 
covite is one of the most common products of alteration. In 
the granites from (jraniteville many very minute, isotropic,, 
strongly refracting grains of secondary origin occur which prob- 
ably are garnets, but on account of their very minute size this 
covdd not be proved. 
A very interesting occurrence was observed in several of the 
granites which seems to be an enlargement of orthoclase indi- 
viduals by a process of secondary growth. In all such cases 
the original crystals are decidedly idiomorphic. The material 
of the secondary growtli is attached to these original crystals 
and is oriented with them. Sometimes the new material ex- 
tentls entirely around the crvstals. as shown in fig. 2, b; in 
other cases only a part of the way, as represented in fig. 2, a. 
In still other cases the border of new feldspar material is con- 
tinuous a portion of the way, the remaining part being occupied 
by a micropegmatite in which the feldspar is attached to the 
original crystal and is oriented with it. This is shown in fig. 3. 
A fourth form, as represented in fig. 
2, c, consists of an entire border of 
micropegmatite in which the feld- 
spar is in rod-shaped portions pro- 
jecting outward from the original 
crystal to which they are attached 
and with which they are oriented. 
Thus there exists a complete series, 
from the feldspar crystals with the 
entire rim of the secondary growth 
to those with the micropegmatite bor- j^ig -j 
derail around. Sometimes cleavage x 40 dicuiieters. 
,. i 1 J- .1 • • 1 a and 6 ai-e from a granite, No. 
hnes extend from the ongmal crys- -{(u. Thej- show the feldspar en- 
, , . .1 ^ j.\ ii. I 1 .L largements. <i. sliows cleavage 
tal out through the attached part, lines passing from the original 
T ,1 .1 ,. • . , crystal into the added portion, a 
In Other cases there are hnes m the is from Xo.2G3, a pegmatite which 
T 1, I 1 • 1 1 L. approaches a granophyre in struc- 
secondary border which do not ex- ^y^. 
tend into the original crystal, and 
which are not parallel to its cleavage lines. In such cases it 
would seem that the growth began as in the mlcrt^pegmatite 
border and continued until the individual rays united forming a 
solid zone. Each one of these rays, of course, would be oriented 
