UNISILICATES. 26k 
Vesuvianite.—Idocrase. 
Wiunerrie. O-t=142°>. 46° 3 1 AlL=129° 21, eS 12 
14’. Cleavage not very distinct parallel with Z| Also found 
massive granular, and subcolumnar. 

Color brown; sometimes passing into green. In some 
varieties the color is oil-green in the direction of the axis 
and yellowish green at right angles with it. Streak un- 
eolored. Lustre vitreous. Subtransparent to nearly opaque. 
H.=65. G.=3°33-3°4. 
Composition. (40a, 2Al),O,Si; A small part of the 
Ca is usually replaced by magnesium, and part of the alu- 
minum sometimes by iron in the sesquioxide state. Per- 
centage of a common variety, Silica 37:3, alumina 16:1, 
iron sesquioxide 3:7, hme 354, magnesia 2-1, iron protox- 
ide 29, water 2:1=99°6. B.B. fuses easily with efferves- 
cence to a greenish or brownish globule. 
Diff. Resembles some brown varieties of garnet, tourma- 
line and epidote, but besides its difference of crystallization, 
it is much more fusible. 
Obs. Vesuvianite was first found in the lavas of Vesuvius, 
and hence the name. It has since been obtained in Pied- 
mont; near Christiania, Norway; in Siberia; also in the 
Fassa Valley. Cyprine includes blue crystals from ‘Telle- 
marken, Norway; supposed to be colored by copper. 
In the United States, it occurs in fine crystals at 
Phippsburg and Rumford, Sandford, Parsonsfield and 
Poland, Me. ; Newton, N. J.; Amity, N. Y. In Canada at 
Calumet Falls, and at Grenville. 
The name idocrase is from the Greek eido, to see, and 
krasis, mixture ; because its crystalline forms have much 
resemblance to those of other species. 
This mineral is sometimes cut as a gem for rings. 
Mellilite in honey-yellow crystals (which includes Hum- 

