APLITE, PEGMATITE, AND TOURMALINE 189 
In the aplite there is an access of Al,O, after deducting 
the amount required of the feldspathic contituent of .0059 mole- 
cules corresponding by weight to 0.6 per cent., which is probably 
combined as mica. From the above calculations the ratio of 
soda feldspar to lime feldspar is 9:1 in the case of aplite and 
17:1 in the case of the granite, corresponding to lime-bearing 
albite of Ab,An, and Ab,, An, respectively, when the albite 
and anorthite molecules are combined to form soda-lime plagio- 
clase. The potash feldspar in both the aplite and granite is 
part orthoclase and part microcline. According to the calcula- 
tions the relative abundance of the constituents in the aplite 
may be expressed as follows: Oligoclase > quartz > orthoclase 
and microcline > muscovite. In the case of the granite the 
potash feldspars are slightly in excess of the quartz, otherwise 
the order of relative abundance of the constituents is the same 
as for the aplite. 
I. II. Iil. IN, Vv. VI. 
SNHOn a saGuocecembe S519) 76.03 76.00 FiAy2il ee Wr Gvo so) 
PDI Ole Siarsiees) Seyeeiavs se 0.09 0.07 0.04 0.30 0.29 | none 
JANA OF eins wma s aver 13.07 13.39 14.88 14.47 UGA | Teg G]B 
WenOn seo 6b a6 yo 0.61 0.48 0.65 0.35 0.29 0.78 
INFO) See aamouan 0.39 Onsir 0.10 0.50 1.04 | Ase 
MnO rience cinieane trace trace trace none trace | none 
Ca@rarcnie ane 1.49 1.28 0.19 tg fal 0.35 0.90 
SO Mie arawliatneces 0.03 trace none trace Be none 
Ba Oi eirecm ne cccears 0.14 0.04 trace none tatene none 
WIGOL batoae. Boda ae 0.14 0.05 0.06 0.28 0.06 (strong trace 
GR Oe Warses steve terete 5.62 5.18 277, 0.10 4.47 4.52 
NasOn wyncwaccctene 2.51 2.98 3.52 FiO 4.64 4.61 
ILIAD) piss slo soe ociod trace none 0.20 trace SB Ho Brea 
HS Okataoons sas: 0.14 Oeus io 0.15 
H,O above 300°... 0.24 On3s4m et 1.42 | 0.23 0.14 0.21} 
Ba Oe eesti acc trace 0.03 0.11 0.07 Souk trace 
100.44 100.33 99.94 99.99 100.66 100.05 
Iand II. Potash aplites. Described by H. W. Turner, Jour. GEOL., 1899, Vol. 
VII, p. 160; also Seventeenth Ann. Rept. U.S. Geol. Surv, p. 521. W. F. Hillebrand 
analyst. 
III and IV. Soda aplites. Described by H. W. Turner, Jour. GEOL., 1899, Vol. 
VII, p. 152. III, W. F. Hillebrand, analyst. IV, H. N. Stokes, analyst. 
V. Aplite. Described by H.S. Washington, Jour. GEOL., 1899, Vol, VII, p 107. 
H. S. Washington, analyst. 
VI. Aplite. Stone Mountain, Georgia. Thomas L. Watson, analyst. 
