ART. 18 MINERALS OF ITALIAN" MOUNTAIN CROSS AND SHANNON 41 



While all of the preceding specimens are described as pyrite, no 

 fresh pyrite remains in them, this mineral in all these cases being 

 now represented by perfect pseudomorphs of limonite. Unaltered 

 pyrite was, however, observed in a few specimens. Embedded imper- 

 fect pyrite crystals up to 4 mm. in diameter occur in limestone 

 which contains vugs lined with siderite and calcite (No. 845T3), and 



b- 



16 17 



Figs. 16-17. — 16, Ckystal of Calcite. 17, Cri'stal of Apatite 



another specimen of the same number shows a thin layer of fresh 

 pyrite underlying a crust of calcite crystals resting on unaltered 

 limestone. A specimen (No. 84562) consisting principally of anor- 

 thite contains scattered partly altered grains and imperfect crystals. 



APATITE 



Apatite forms small yellowish-white to colorless transparent crys- 

 tals up to 3 mm. in diameter by 6 mm. long interspersed with 

 sahlite crystals in cavities in solid masses of sahlite and occurs also 

 as transparent pale greenish crystals embedded in calcite and ill- 

 defined brownish masses up to 2 cm. long embedded in sahlite 



