168 PHYSIOGRAPHY. 



Compound Varieties. Botryoidal, reniform, 

 massive: composition generally impalpable, sur- 

 face drusy or rough, fracture imperfect and flat 

 conchoidal, lustre faint resinous. 



Alone 4 before the blowpipe it intumesces a little, and 

 then froths and melts into a greyish globule, giving at the 

 same time some globules of lead. In the oxidating flame a 

 small quantity effervesces with, and imparts a green colour 

 to borax and salt of phosphorus, which remains transpa- 

 rent on cooling ; but in the reducing flame the globule 

 turns red and transparent, or red and opake, or finally 

 black, according to the quantity of the mineral employed. 

 According to BERZELIUS, it consists of 



Oxide of Lead 60-87. 



Oxide of Copper 10-80. 



Chromic Acid 28-33. 



It occurs at Beresof in Siberia, along with hemi-prisnia- 

 tic and rhombohedral Lead-baryte, and has been quoted 

 also from Brazil, where it likewise accompanies the hemi- 

 prismatic Lead-baryte. 



VELVET-BLUE COPPEB. 

 MALACHITE ? 



Velvet-Blue Copper. JAM. Syst. Vol. II. p. 320. Man. 

 p. 332. 



Short capillary crystals, in velvety druses and 

 coatings. 



Lustre pe$rly. Colour bright smalt-blue. Trans- 

 lucent. 



It has been found lining drusy cavities in prismatic Iron- 

 ore, only at Moldawa in the Bannat of Temeswar, accom- 

 panied by several ores of copper. This rare substance is 

 very imperfectly known, and also its chemical composition 

 has not been ascertained. 



