GUIDE TO THE MIXERALOGIC COLLECTIONS 



101 



columnar and granular masses. The luster is vitreous to dull, 

 and the color is usually gray, dull green or white, sometimes 

 bluish or reddish. 



YVernerite occurs in metamorphic rocks and is abundant in 

 granular limestone near the contact with granite or other igne- 

 ous rocks. It is associated with pyroxene, am- 

 phibole, apatite, etc. In New York wernerite 

 is found in Orange, Essex and Lewis counties 

 and abundantly in Jefferson and St Lawrence 

 counties. 



Vesuvianite (idocrase) 



Vesuvianite is a basic calcium-aluminium 

 silicate of uncertain formula with some of 

 the calcium replaced by manganese and 

 some of the aluminium by iron. Fluorin and titanium may be 

 present. 



The crystals are tetragonal, prismatic or pyramidal in habit, 

 the prismatic crystals often exhibiting the general type shown in 

 fig. 220. Columnar masses occur straight, radiated or irregular, 

 often producing characteristic striations parallel to the vertical 

 axis. The luster is vitreous to resinous and the 

 color commonly brown, green or some interme- 

 diate shade, rarely yellow or blue. 



Vesuvianite commonly occurs as a contact min- 

 eral from the alteration of impure limestone; also 



in serpentine, chlorite schist, gneiss and other 



Fig. 220 

 Vesuvianite 



metamorphic rocks; in the former case it is usually 

 associated with garnet, phlogopite, pyroxene, wollastonite, etc. 

 It is found in Canada, Maine, New Hampshire and New Jersey 

 and in Orange county and other localities in New York. 



Zircon (hyacinth) ZrSi0 4 



Zircon is a silicate of zirconium usually containing a little 

 iron sesquioxid. 



It occurs in tetragonal crystals, prismatic in habit, of the 

 general types shown in fig. 221-23, but sometimes pyramidal 

 with the prism only slightly developed. Twins similar to those 

 of cassiterite and rutile occur. Zircon is also found in irregular 

 lumps and grains. The luster is adamantine and the color 



