PALACHE AND FRAPRIE. — BABINGTONITE. 385 



developed to permit of measurement, but they appear to be dominated by 

 the cube. 



Chlorite is not common with the babingtonite, but is apt to occur 

 intermixed with the massive form of tha prehnite. 



Feldspar is found with prehnite and babingtonite in a few specimens, 

 in the form of small imperfect pinkish crystals. They are similar in 

 appearance to the pinkish labradorite of the enclosing diabase and were 

 not further determined. This mineral is found only in certain pockets 

 of oval form entirely enclosed in the diabase. The dyke at this point 

 contains many inclusions of various rocks, and it is probable that these 

 pockets represent inclusions in which the original material has been 

 almost wholly replaced by prehnite and calcite. Wadsworth* found 

 pseudomorphs of prehnite after feldspar here, which fact to some extent 

 strengthens this conclusion, based chiefly upon the form of the pockets. 



Calcite occurs in both veins and pockets as the last substance deposited, 

 filling up all the interstices of the other minerals. It is white and glassy, 

 often in large individuals, but never, so far as observed, in developed 

 crystals. Near the surface of the veins the calcite has generally been 

 removed by solution, but away from the zone of weathering it seems 

 always to be present, and all the finer specimens of prehnite and bab- 

 ingtonite were obtained by dissolving away the infilling of calcite with 

 dilute acid. 



Of the remaining minerals recorded above from the locality one only, 

 chabazite, has been seen by the authors. It occurs in well-formed twin 

 rhombohedrons, pure white in color, implanted on a specimen of massive 

 prehnite. The specimen was not collected by us and this mineral has 

 not been found at the locality for some years. 



The babingtonite is usually in distinct crystals implanted upon, and 

 in rare instances wholly embedded in, prehnite. The crystals are often 

 but slightly attached to the prehnite, and are therefore not infrequently 

 completely bounded by crystal planes. They are generally small, rarely 

 exceeding 2 or 3 mm. in greatest dimension ; but a few larger crystals 

 were obtained, the largest measuring 1.5 x 1 X.4 cm. The complete 

 detached crystal shown in figure 3 is 1 X.7 X.2 cm. and is perhaps the 

 largest perfect crystal preserved from the locality. Granular aggregates 

 of babingtonite are also found embedded in prehnite, composed sometimes 

 of fine grains and again of individuals so large that cleavage surfaces of 

 several square centimeters' area may be observed. 



» 



* Loc. cit., p. 223. 

 vol. xxxviii. — 25 



