418 



MR. J. PARKINSON ON THE GEOLOGY OE 



[Aug. 1903. 



conspicuously idiomorphic when surrounded by the former mineral. 

 Conspicuous also are rounded nodules of quartz-grains, spangled 

 with minute specks of mica and calcite, recalling amygdaloids by 

 their shape, though some may have been produced by the alteration 

 and replacement of a felspar. The last-named mineral occurs in 

 recognizable form, twinned and of low extinction-angles, sometimes 

 a twentieth of an inch across. The carbonates of the lenticles are 

 associated with grains of quartz in such a connection as might be 

 produced by corrosion, The quartz forms rounded grains, some- 

 times embaying the carbonate-granules in blunt tongues, at others 



Fig. 3. — Rode from 



•'.•.*4">#</ 



[Part of a lenticular aggregate of calcite (dotted) and quartz, surrounded by 

 the reconstructed groundmass, containing specks of iron-oxides, mica-flakes , 

 etc. Biotitei,(6) is conspicuous, frequently associated with epidote (e).] 



enclosing particles within its substance. These globular particles 

 are not infrequently attached to an adjacent grain of calcite or 

 dolomite, as though the process of isolation were incomplete. 

 Resembling the quartz in habit and appearance are grains of a 

 translucent felspar, agreeing in extinction with albite. 



A thin section of the rock from Eossiney Haven, cut parallel to 

 the foliation and through one of the less calcareous laminae, shows 

 a plexus of very elongated crystals of epidote embedded in a uniform 



