GUIDE TO THE MINERALOGIC COLLECTIONS 



125 



Fibrous, granular and marblelike masses occur, sometimes 

 exhibiting a sugarlike appearance on the fracture. The color 

 is commonly white or gray, often bluish, reddish or brick-red. 

 The luster is vitreous inclining to pearly. 



Anhydrite occurs associated with rock salt, gypsum and lime- 

 stones of various ages. It is found in New Brunswick and Nova 

 Scotia and to a limited extent at Lockport X. Y. and in eastern 

 Pennsylvania and Tennessee. 



Anglesite PbS0 4 



Anglesite is a sulfate of lead containing 26.4 r f sulfur trioxid 

 and 73.6^ lead oxid. 



The crystals are orthorhombic and of varied habit. Massive 

 forms are extremely common, the mineral frequently forming 

 in concentric layers around a core of galena. Anglesite is 

 white, gray or more rarely bluish or yellowish in color; the 

 crystals are often transparent and colorless. The luster is 

 adamantine to vitreous. 



It is a frequent decomposition product of galena with which 

 it is commonly associated and often alters to cerussite. It is 

 found throughout the United States in the lead regions notably 

 in Pennsylvania. Missouri, ^Yisconsin and Colorado. Extensive 

 deposits occur in Mexico and Australia. 



It is mined with other lead minerals as an ore of lead. 



' Celestite SrS0 4 



Celestite is a sulfate of strontium sometimes containing small 

 amounts of calcium and barium. 



It crystallizes in the orthorhombic system in forms generally 

 similar in type to those of barite, often tabular parallel to the 

 base or prismatic to the macro or brachy 

 axes (fig. 244). Fibrous massive forms 

 occur with a parallel or radiated silky 

 structure; also cleavable masses and more 

 rarely granular varieties. In color celes- 

 tite varies from white to pale blue, some- 

 times reddish; the crystals are often trans- 

 parent and colorless. The luster is vitre- Fi s- 244 



1 ' Celestite 



ous to pearly. 



Celestite is of frequent occurrence in limestone and sandstone, 

 in beds of gypsum, rock salt, etc.; and in volcanic regions asso- 



