1826. J Mr. Levi/ vn Tioo new Minerals. 195 



and slightly curved, and this last circumstance gives to the crys- 

 tals, which are rather elongated in the direction of the axis, 

 something of a barrel shape. For the same reason the incidence 

 of the lateral planes could only be obtained by approximation 

 by means of the common goniometer, and appears to be about 

 105°. A right rhombic pn'sm of 105° may, therefore, be consi- 

 dered as the primitive form. The ratio between one side of the 

 base and the height has not been determined, because the angle 

 of P on e, fig. 3, could not be measured with sufficient accuracy. 

 The hardness of the substance is nearly the same as that of sul- 

 phate of lime, and it is very easily pounded. The crystals are 

 closely engaged together, and are placed upon amorphous ferru- 

 ginous oxide of copper. The locality is Werchoturi, in Siberia. 

 From the examination of a very small quantity of this substance 

 by Dr. WoUaston, it appears to consist principally of sulphuric 

 acid and oxide of copper, and might, perhaps, be considered as a 

 subsulphate of copper. This result shows a great analogy 

 between Konigine and Brochantite, which last mineral, examined 

 by Mr. Children, was also found to consist principally of sulphuric 

 acid and oxide of copper. The hardness, colour, matrix, and 

 locality, of the two substances seem also to be nearly the same, 

 but their forms appear to be totally different. Brochantite occurs 

 in thin rectangular tables whose angles are truncated and edges 

 bevelled, without any appearance of cleavage. Konigine, on the 

 contrary, is met with in barrel-shaped crystals, with an easy and 

 most brilliant cleavage in a direction perpendicular to the axis. 

 When these two very rare substances may be procured in large 

 quantities, it will, however, be worth the attention of mineralo- 

 gists and chemists to compare them again. 



Beudavtite. 

 This substance occurs in small crystals closely aggregated, of 

 the form represented by fig. 4, which is a 

 slightly obtuse rhombohedron with the j,. ^ 



summits truncated. Their colour is black '^' 



at the surface, and their lustre somewhat 

 resinous, but thin fragments are translu- 

 cent, and of a deep-brown colour. They 

 cleave easily in only one direction parallel 

 to the face a', or perpendicular to the axis 

 of the rhombohedron. This face of cleav- 

 age, however, is not sufficiently brilliant to 

 allow the use of the reflective goniometer 

 to measure its incidences upon the planes 

 of the rhomboid. These planes themselves are generally brilliant, 

 but sometimes slightly curved. The mean of several measure- 

 ments obtained by the reflective goniometer has given for the 

 incidence of P oa P, 92° 30'. The primitive form of Beudantite 



o2 



