GUIDE TO THE MIXERALOGIC COLLECTION'S 



119 



It occurs in hexagonal crystals of the pyramidal group, pris- 

 matic in habit, often in rounded or barrel-shaped forms or in 

 parallel and branching groups (pi. 36 2 ), less frequently in globu- 

 lar and reniform masses with a subcolumnar structure. The 

 luster is resinous and the color usually some shade of green, 

 yellow or brown, also grayish white or milk-white. 



Pyromorphite occurs principally in veins with galena and 

 other lead minerals. It is found in Saxony, Bohemia and 

 Nassau and in several places in England and Scotland. In the 

 United States it occurs in Maine, Pennsylvania, North Carolina 

 and at Ossining N. Y. 



Mimetite (PlCl)Pb 4 (As0 4 ) 3 



Mimetite is an arsenate of lead with lead chlorid. With the 

 replacement of arsenic by phosphorus it grades into pyromor- 

 phite; calcium also frequently replaces part of the lead. 



The crystals of mimetite are hexagonal-pyramidal and 

 resemble those of pyromorphite; they show, how T ever, a marked 

 tendency toward the production of rounded, globular aggre- 

 gates (pi. 37J. The mineral also occurs in mammillary crusts. 

 The luster is resinous and the color yellow to brown or white. 

 Its occurrence is similar to that of pyromorphite. 



Vanadinite (PbCl)Pb 4 (V0 4 ) 3 



Vanadinite is a vanadinate of lead with lead chlorid. Phos- 

 phorus is also often present in small amounts; also arsenic, 

 both of which replace some of the vanadium. 



The crystals are like those of pyromorphite 

 and mimetite, often with hollow or cavernous 

 faces on the basal plane, and sometimes show- 

 ing the modification of the third order pyramid 

 (fig. 238). The luster is resinous and the color 

 deep red, brown to yellow. 



Vanadinite abounds in the mining regions of 

 Arizona and New Mexico where it is associated 

 with wulfenite. 



Vanadinite is a source of vanadium salts, which are used in 

 dyeing fabrics, and for the production of vanadium bronze, 

 vanadium ink, etc. 



