ART. 18 MINERALS OF ITALIAN MOUNTAIN CROSS AND SHANNON 



9 



alteration of the sediments in any other locality. The presence of 

 chlorine and fluorine in mizzonite and epidote, respectively, on 

 Italian Peak shows that unusual mineralizers accompanied the quartz 

 monzonite magma in that particular intrusion, but it seems unwar- 

 ranted to assume that any large part of the extensive mineral forma- 

 tion was due to the activity of these agents. 



The greatly folded and faulted or crushed condition of the sedi- 

 ments in the mineralized area has been emphasized. It seems prob- 

 able that the high permeability of the intruded rock complex by 

 solutions or gases was the most important factor in the case. 



DESCRIPTION OF THE MINERALS 



By Earl V. Shannon 



In the collection of some 200 specimens from the Italian Mountain 

 locality 28 minerals were observed. These are described in some 

 detail in the following pages in the order listed below. 



1. Garnet. 



2. Diopside. 



3. Sahlite. 



4. Vesuvianite. 



5. Epidote. 



6. Albite. 



7. Anorthite. 



8. Orthoclase. 



9. Titanite. 

 10. Talc. 



11. Chlorites. 



12. Mizzonite. 



13. Quartz. 



14. Scolecite. 

 Thomsonite. 

 Stilbite. 

 Heulandite. 

 Chabazite. 

 Graphite. 



15, 

 16, 

 17 

 18 

 19 

 20, 



21. Hematite. 



22. Chalcedony 



23. Siderite. 



24. Ankerite. 



25. Calcite. 



26. Pyrite. 



27. Apatite. 



28. Barite. 



Magnetite. 



GARNET 



Garnet is the most abundant mineral in the collection and occurs 

 in a variety of forms, habits, and colors, and exhibits considerable 

 variation in composition and associations. 



The most abundant garnet is pale buff in color, varying to almost 

 colorless in some specimens. This forms more or less well-developed 

 crystals varying from 1 mm. to nearly 4 cm. in diameter. The aver- 

 age color is light buff but varies from practically colorless through 

 various shades of light brown to greenish buff or green. This 

 garnet occurs lining open spaces in massive garnet or garnet-diopside 

 hornfels as loosely assembled aggregates of large garnets or as 

 druses along the open centers of seams. Some of the crystals are 

 transparent, most of them from translucent to opaque in the speci- 

 men. The smaller crystals are the most perfectly developed. All 

 48180—27 2 



