300 



METALS. 



inferior hardness. It is a valuable ore when abundant ; but 

 it- is seldom smelted alone, because the metal is liable to es- 

 cape with the liberated volatile ingredient — carbonic acid. 



azurite. — Blue Carbonate of Copper. 



Monoclinic. In modified oblique rhombic prisms, the 

 crystals rather short and stout; 

 lateral cleavage perfect. Also 

 massive. Often earthy. 



Color deep blue, azure or Ber- 

 lin-blue. Transparent to nearly 

 opaque. Streak bluish. Luster 

 vitreous, almost adamantine. — 

 Brittle. H=3*5— 4-5. Gr= 

 3-5—3-85. 



Composition: carbonic acid 25*6, oxyd of copper 69-2, 

 water 5-2. Before the blowpipe and in acids, it acts like 

 the preceding. 



Obs. Azurite accompanies other ores of copper. At 

 Chessy, France, its crystallizations are very splendid. It is 

 found also in Siberia, in the Bannat, and near Redruth in 

 Cornwall ; at Phenixville, Pa., in crystals. 



As incrustations and rarely as crystals, it occurs near 

 Singsing, N. Y. ; near New Brunswick, N. J. Also near 

 Nicholson's Gap, in the Blue Ridge, Penn. 



Uses. When abundant it is a valuable ore of copper. It 

 makes a poor pigment, as it is liable to turn green. 



chrysocolla. — Silicate of Copper. 



Usually as incrustations ; botryoidal and massive. Also 

 in thin seams and stains : no fibrous structure apparent., nor 

 any appearance of crystallization. 



Color bright green, bluish-green. Luster of st iT *face ot in- 

 crustations smoothly shining ; also earthy. Translucent to 

 opaque. H=2 — 3. Gr = 2 — 2*3. Composition: — 





SIBERIAN. 



V. Kobell. 





Berthier 



NEW JERSEY. 

 Bowen. 



Beck. 



Oxyd of copper 



40 





551 



452 



426 



Silica 



365 





354 



373 



400 



Water 



202 





28-5 



170 



160 



Carbonic acid 



21 



loss 



10 











Oxyd of iron 



1-0. 













1-4 



Describe blue malachite. How does it differ from green malachit 

 in composition 1 What is- the appearance of chrysocolla ? its composi 

 tion 1 



