138 



SILICA. 



y 



<* 



a 



yellowish or reddish brown. Sandstone often consists of 

 nearly pure quartz. 



Silic'jied wood. Petrified wood often consists of quartz. 

 Some specimens, petrified with chalcedony or agate, are 

 remarkably beautiful when sawn across and polished, re- 

 taining all the texture or grain as perfect as in the original 

 wood. 



Penetrating substances. Quartz crystals are sometimes 

 penetrated by other minerals. Rutile, asbestus, actinolite, 

 topaz, tourmaline, chlorite and anthracite, are some of these 

 substances. The rutile often looT^Hikc needles or fine hairs 

 of a brown color passing through in every direction. They 

 are cut for jewelry, and in France pass by the name ofFleches 

 d'amour, (love's arrows.) The crystals of Herkimer county, 

 N. Y., often .. contain anthracite. Other crystals contain 

 cavities filled with some fluid, as water, naphtha or some 

 , mineral solution. 



hoc. Fine quartz crystals occur in Herkimer county, 

 New York, at Middlefield, Little Falls, Salisbury and New- 

 port, in the soil and in cavities in a sandstone. The beds of 

 iron orfcs at Fowler and Hermon, St. Lawrence county, af- 

 ford dodecahedral crystals. Diamond rock near Lansing- 

 burg is an old locality, but not affording at present good 

 specimens. Diamond Island, Lake George, Pelham and 

 Chesterfield, Mass., Paris and Perry, Me., and Meadow Mt., 

 Md., are other localities. Smallunpolished rhombohedrons, 

 the primary form, have been found at Chesterfield, Mass. 

 Rose quartz is found at Albany and Paris, Me., Acworth, 

 N. H., and Southbury, Conn. ; smoky quartz at Grusiretty 

 Mass., Paris, Me., and elsewhere ; amethyst at Bristol, R. I., 

 and Kewenaw Point, Lake Superior ; chalcedony and agates 

 of moderate beauty near Northampton, and along the trap of 

 the Connecticut valley-*-but finer near Lake Superior, upon 

 some of the Western rivers, and in Oregon ; chryroprase 

 occurs at Belmont's lead mine, St. Lawrence county, N. Y., 

 and a green quartz (often called chryroprase) at New Fane, 

 Vt., along with fine drusy quartz ; red jasper occurs on the 

 banks of the Hudson at Troy, and at Saugus near Boston, 

 Mass. , yellow jasper is found with, chalcedony at Chester, 

 Mass. ; Heliotrope occupies veins in siate at Blooomingrove, 

 Orange county, N. Y. 



What is granular quartz ? What is said of silicified wood ? Whal 

 are common penetrating substances ? 



