300 METALS. 



J ^ferior 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. 



azukite. — Blue Carbonate of Copper. 

 Monoclinic. In modified oblique rhombic prisms, thd 

 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. 1 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. 

 i 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 surface ot in- 

 crustations smoothly shining ; also earthy. Translucent to 

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



SIBERIAN. NEW JERSEY. 



V. Kobell. Berthier. Bowen. Beck. 



V 



Oxyd of copper 400 55*1 452 426 



♦Silica 36-5 354 373 400 



Water 202 28-5 170 160 



Carbonic acid 24 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 1 its compos 

 tion? 



