350 



MINERALOGY 



B.B. Infusible. In the S. Ph. bead beside tin on coal yields 

 a violet color when cold; the bead powdered and dissolved in 

 concentrated HC1, then reduced with powdered tin, yields a violet 

 solution. Insoluble in acids. 



General Description. Rutile occurs in all varieties of rocks, 

 igneous, metamorphic, and sedimentary, either as short stout, or 

 elongated and acicular prisms, with striations on the prism zone 

 parallel to the c axis ; very often these long, hairlike crystals are 



found penetrating 

 clear quartz, as at 

 St. Gothard, Switz- 

 erland, when the 

 specimens are pol- 

 ished and cut as 

 ornaments. At this 

 same locality small 

 prismatic rutile 

 crystals are found 

 placed in parallel 

 position on hex- 

 agonal plates of 

 hematite. At 

 Tavetsch, Switzer- 

 land, reticulated, 

 platelike masses of 

 elongated crystals, 

 interlocking at the 

 twinning angle of 

 65 35', occur and 

 are known as sage- 

 nite. 



Rutile in the 

 United States has 

 been mined in Vir- 

 ginia, where it is 

 found near Arring- 

 ton in a pegmatite; at Nelson it is associated, in dykes, with 

 apatite; at Lynchburg beautifully formed crystals with a steel- 

 like luster, both simple and twinned, are common, as also in Alex- 

 ander County, North Carolina, and at Graves's Mountain, Georgia. 



FIG. 419. Acicular Crystals of Rutile included in 

 Quartz. Japan. 



