ART. 18 MINERALS OF ITALIAN MOUNTAIN CROSS AND SHANNON 13 



grossiilarite. Such a garnet has a calculated gravity of 3.651, while 

 the measured specific gravity is given as 3.721 at 17.2° C. 



A third lot of garnet (No. 84550) from the north side of the 

 gulch leading north of North Italian Mountain contains four speci- 

 mens. The garnet is in brown, more or less globular masses, ranging 

 • from 1 to 6 mm. in diameter. These are scattered sparsely through 

 dirty white granular marble and are conspicuous on weathered sur- 

 faces. When closelj^ examined the globules are found to be made 

 up of innumerable very minute dodecahedral units in parallel posi- 

 tion. The powder of these garnets is pale brown, and under the 

 microscope they exhibit a peculiarly wavy appearance and compara- 

 tively strong birefringence. They are probably andradite, since the 

 refractive index is much higher than 1.80. 



Distinctly green garnets were seen in several specimens. Beauti- 

 fully sharp little green dodecahedral garnets 2 mm. m diameter, 

 lining a cavity of garnetiferous hornfels of one specimen (No. 84551) 

 from Italian Mountain, have a beautifully iridescent metallic sheen 

 or luster. A few stilbites were deposited on them, followed by a 

 layer of chabazite, and then the cavity was filled with calcite. They 

 are now exposed where the calcite has dissolved away. Another 

 specimen (No. 84576) has a druse of 1 to 2 mm. green dodecahedral 

 garnets crusting garnet hornfels and overlain by little crystals of 

 adularia and pyrite. 



One specimen (No. 84551) consists of small opaque-appearing 

 sharp dodecahedral brown garnet crystals up to 2 mm. in diameter, 

 thickly scattered in white calcite and making up a granular rock. 



Two specimens show garnet crj^stals which display an unusually 

 sharp color zoning (No. 84558). These occur in veins up to 2 cm. 

 wide in fine-grained green diopside rock. The garnet crystals over- 

 lie diopside prisms and are themselves overlain by epidote and calcite. 

 The garnet crystals are dodecahedrons narrowly truncated by the 

 trapezohedron and reach 1 cm. in diameter. The cores of the garnets 

 are deep red-like almandite with an outer border about 1 mm. thick 

 of pale buff material and a very thin outside brown shell. The 

 indices of all parts of the crystals are well above 1.80, so that the 

 material is doubtless andradite with varying amounts of the grossu- 

 iarite molecule. 



A specimen of highly graphitic schist from North Italian Moun- 

 tain (No. 84552) contains numerous black dodecahedral garnets aver- 

 aging 5 mm. in diameter. "Wlien powdered this garnet is black and 

 white, and under the microscope it is seen to owe its black color to 

 black opaque inclusions, doubtless of graphite. The garnet itself is 

 colorless in section and isotropic with an index of refraction of 

 1.742 to 1.744. 



