84 PHYSIOGRAPHY. 



Bournonite. 



Surface nearly equal, often highly smooth and splendent: 

 longitudinal striae sometimes visible on the secondary planes, 

 replacing the lateral edges of the prism. 



Lustre metallic. Color steel grey, inclining to blackish 

 lead grey or iron black, according to the physical quality 

 of the surface. Streak unchanged. 



Brittle. Hardness =2-5 . . . 3-0. Sp. gr. =5-763. 



Compound Varieties. Twin-crystals : axis of revolu- 

 tion perpendicular, face of composition parallel to M, or the 

 broader face of the primary form. The individuals are 

 generally continued beyond the face of composition. The 

 axes of the individuals cross each other at angles of 93 40' 

 and 86 20'. Massive : composition granular ; individu- 

 als strongly connected. 



1. Before the blow-pipe, it generally decrepitates, emits a white sul- 

 phureous vapor ; after which there remains a black globule, consisting 

 of a crust of sulphuret of lead, within which is a mass of copper. It is 

 easily soluble in heated nitric acid. 



2. Analysis. 



By HATCHETT. Ey KLAPROTH. 



Antimony . . 24-23 . . 20769 



Lead , . . 42-62 . . 42-50 



Copper . .. 1280 . . 11-75 



Iron . . 1-20 .. 5-00 



Sulphur . . 17-00 . . 18-00 



3. Bournonite is found in veins, associated with Stibine, Galena, and 

 Blende. 



4. It was first found in the parish of Endellion, Cornwall, at Huel 

 Boys. Another locaUty, very early known, was Kapnik in Transylva- 

 nia. It is now known to exist at Neudorf, in Anhalt, in large and mag- 

 nificent crystals; also at Andreasberg in the Hartz. Still other deposits 

 of this ore are BraQnsdorf in Saxony, Neusohl in Hungary, and OfFen- 

 banya in Transylvania. 



