

36 



BULLETIN OF THK 



ca,vity and are distinctly separated fi'om it. They uj-c filled with cpi- 

 dote, chlorite, calcite, quartz, and a fii)rous chalcedonic (?) material : 

 the epidote is generally on the outside, tlic chlorite inside. Consider- 

 able epidotc is seattered througli the section, generally outside of the 

 feldspars, and also talc, caloito, and quartz. 'J'heso dcconiposiLion ]}rod- 

 nets often occnr in th.e groundmass in rounded areas, but are not true 

 amygdaloids. Patches of reddish opaqne ferrite also occur in a similar 

 manner, constituting the red spots seen macroscopically. 



[5.] Western Ridije of the Dike cm the West Side of a Road which crosses 



it, — taken towards the Cadre of Uie Mass. 



Lens. A greenish groundmass containing porphyriiio feldspars, red- 

 dish and greenish areas of alteration, and rounded masses of (piartz. 

 The groundmass has intruded into some of the large feldspars. 

 Section. Crystals of feldspar and areas of decomposition or iufiltration 

 surrounded by a greenish chloritic mass. The Luge ieldsi)ars ar(! occa- 

 sionally Carlsbad twins; the small ones of the groundmass piincipally 

 plagioclase, although some are twinned sanidin crystals. The (original) 

 base, carrying small feldspars, has bent some of the laigo feldspars, and 

 pushed into them. Others contain in the centre square zonsd inclusions 

 of the greenish mass, while the outer zone of the crystal is free frum 

 it. These phenomena are similar to those so frequently observed in the 

 unaltered basalts with a glassy base. Many of the hirger feldspar cr)'sLals 

 are partly filled with epidote grains,, chloritic material, and light^green 

 needles, which have a yellowish-white polarization. Ptouuded areas, com- 

 posed of greenish chloritic fibres, with sometimes a deep violet blue 

 color between Crossed nicols, occur in the groundmass, niiu<dcd occa- 

 sionally with talc, and bordered by epidote. Some of these ai'cas, en- 

 closing the remains of the small feldspars, arise fi-om the decomposition 

 of the groundmass ; others are either true amygdules, as described above, 

 or some might be pseudomorphs after some mineral, — for instance, oli- 

 vine. Between the feldspars lies tlie gi'een mixture of chlorite, viridite, 

 and greenish needles f^imilar to those described in the feldspars, beside 

 some epidote, calcite, and quartz. 



[G.] Western Ridije of the Amygdaloid, ahout fifty feet east of a Road 

 crossing it, ~ the Specimen taken from, a long Dike crossing the 

 Amygdaloid obUqnely to its 'Main Trevd. 



A grayisli-grcen groundmass, holding crystals of greenish 

 feldspar and grains of ])yrite. The groundmass has pushed into some of 



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