1917] Eakle: Minerals Associated with Crystalline Limestone 349 



MINERALS ASSOCIATED WITH THE INTRUSIVES 



Feldspars. — Orthoclase, microcline, oligoclase, and labradorite are 

 present in the quarries as constituents of the igneous rocks. Ortho- 

 elase appears to predominate and it forms the larger part of the 

 pegmatites. It occurs red and white. An analysis of the pure white 

 from the pegmatites gave : 



Si0 2 



64.54% 



A1A, 



20.86 



Fe 2 3 



tr. 



CaO 



1.86 



MgO 



tr. 



Ign. 



0.52 



Na,0 



1.18 



K.,0 



11.85 





100.81 



G= 2.54 



Pyroxene. — Besides the good crystals of diopside which are scat- 

 tered through the calcite, there is a deep green pyroxene resembling 

 omphacite, mixed with cinnamon-garnet, which has formed at the 

 contact of the pegmatite and limestone. 



Augite. — Occurs as a constituent of the quartz-monzonite porphyry. 



Hornblende and Biotite. — Both of these minerals are constituents 

 of the granodiorite, the hornblende greatly predominating. Neither 

 seems to occur in the monzonite or pegmatite. 



Titanite. — Granular titanite is rather abundant in the monzonite 

 as a constituent. It occurs pale brown with a marked pleochroism to 

 deeper brown. None of the grains has a crystal boundary. 



Zircon. — Minute crystals and larger grains of zircon are scattered 

 through some of the white pegmatite rock. The color of the mineral is 

 clove-brown and some of the crystals show the forms (100), (110), 

 (111), (331). 



Epidote. — Deep green epidote occurs as one of the contact min- 

 erals of the Commercial Rock quarry. Slender and long crystals and 

 grains are imbedded in some of calcite masses. The mineral is very 

 prominent as a constituent of the pegmatites and is one of the original 

 minerals of the rock. It is present in the pegmatite as long slender 

 crystals having a prominent basal cleavage. The fresh crystals are 

 deep leek-green, but most of them have altered to a bronze-brown and 

 resemble astrophyllite. The elongation of the crystals is parallel to 



