OP ARTS AND SCIENCES. 299 



Ossipee Amygdaloid. — A specimen from an amygdaloid, 725 feet 

 east of the Calumet Conglomerate, on the Ossipee location, has a com- 

 pact, amorphous-looking, soft, dark-green, and brown matrix. It con- 

 tains numerous very irregular spots and patches of prehnite, from the 

 size of a pin-head to several inches. These are in places more or less 

 altered — some wholly — to a liglit and dark-green, soft, chloritic sub- 

 stance, which has conchoidal fracture, and appears amorphous, even 

 under a strong loupe. In some of the amygdules this chloritic product 

 is associated with intermingled calcite ; in others, with quartz. The 

 larger patches of prehnite contain druses, some of which were formed 

 by removal of prehnite substance, while others seem to represent 

 former cavities, and are now lined \ inch thick with reniform prehnite, 

 now much altered and easily scratched. These druses are half filled 

 with small well-formed crystals of epidote and orthoclase, and isolated 

 ones of copper. These sit upon the altered prehnite. The epidote, 

 in minutely granular aggregates, penetrates the reniform masses of 

 prehnite in such a manner as shows it to be pseudomorphous after 

 the latter. The orthoclase crystals, in places, sit directly on the altered 

 prehnite ; in others, on the epidote crystals. The copper is also younger 

 than the epidote. A thin section shows that the matrix has been 

 prehnitized, while some of this prehnite is still present : a large part 

 of it is changed to the pseudo-amygdaloidal chlorite, still preserving 

 the plagioclase outlines. 



A small specimen from an imhnoxon locality in Ontonagon County, 

 has a very soft purple matrix, which is impregnated with aggregates 

 and crystals of epidote. It contains also irregular druses, lined with 

 small epidote crystals, on which sit crystals of copper; and on these 

 again, as well as on the epidote, crystals of orthoclase. 



Bunches of minute, light, gray-green prisms of a very soft mineral 

 sit on the epidote crystals. In so far as external appearance and all 

 the optical tests that can be applied under the microscope go, this min- 

 eral is identical with that which, alone and included in quartz, forms 

 amygdules in the cupriferous amygdaloid of the Pewabic and other 

 mines. That from the Pewabic mine was analyzed by Macfarlane,* 

 with the following result : — 



* Geol. of Canada, 1866, p. 153. 



