THE WEST AMEHICAl!^ SCIENTIST. 65 



FELDSPAR, 



The different minerals Ijelonging to the feldspar group are composed <5f silica, alu- 

 mina, and soda, lime, oi potash. They are distinguished from other minerals by 

 their perfect cleavage in two directions, leaving faces that arc smooth and reflect the 

 light with a peculiar flash. They are harder than limestone and softer than quartz, 

 which two they most resemlDle, and are not decomposed rap'dly by hydrochloric acid 

 and wi;h effervescence like limestone. 



The more common white varieties are mined and used extensively in the arts, 

 and the decomposition of feldspathic rocks results in clay used from time im.memo- 

 rial in the manufacture of pottery. 



The Boston "JournaS. of Commerce," mentioning some of the more precious 

 kinds, says: 'Amazon stone is a bluish green variety of the common kind of fold* 

 spar called orthoclase. In composition it is a silicate af alumina and potash. It is 

 an opaque stone with a somewhat pearly Instre, and a hardness of 6, or 6.5, just be» 

 low quartz. It is quite brittle, but takes a good polish. It was first discovered on 

 the banks of the Amazon, from which circumstance it takes its name. It is found 

 at Lake Baikal, in Siberia, and Pike's Peak, Colorado; also in Korth Carolina, and 

 Mt. Desert, Me. 



Moonstone, or adularia, agrees in composition and hardness with Amazon stone. 

 It has a pearly or silvery reflection not unlike that of the moon, from which it takes 

 its name. It belongs to the cheaper grade of gems, though in some parts of Europe 

 it has at times been much esteemed. The finest specimens come from Geylon. It 

 is found in this country at Medina, Penn., and in Virginia. 



Suns tone is like moonstone in composition and hardness. It is of a yellowish 

 color, reflecting sparkles of light in various directions, owing to minute particles of 

 iron oxide which are disseminated through it. It is found in Siberia, Norway, Cey- 

 lon, and in the United States in the same localities as moonstone. It is also called 

 adventurine feldspar. 



Labradorite, or Labrador spar, is a variety of feldspar of various shades, the kind 

 used in jewelry having a rich blue color. In composition it is a silicate of alumina^ 

 lime and soda, with a hardness of 6. It is remarkable for its beautiful play of col- 

 cars, and its sparkling reflections, like aventurine feldspar. Though generally blue, 

 green, yellow and red kinds are not uncommon, sometimes pearly gray. Labrador- 

 ite was first found on the coast of Labrador, toward the latter part of the last cen- 

 tury, but has since been discovered in Norway, Sweeden, Russia, Canada, and in 

 this country in New York, Pennsylvania, and various other places.' 



The curious and remarkable discovery is reported that a South American shrub 

 called *aliza,* exudes a juice which acts so powerfully in stopping flows of blood 

 that when a knife is smeared with it and used for surgical operations, the largest 

 vessels may be severed without any hemorrhage. 



A scorpion was placed in confinement in a well ventilated tin can on the 26th 

 of May, and lived without food till about the 29th of June. 



