462 LIST OF MINERALS, THEIR 



octahedron, the axis perpendicular to this 

 base being very disproportionately length- 

 ened. 



earthy. Tile ore. 

 phosphate. 



anhydrous. 



crystallised. In the absence of distinct clea- 

 vage, a right rhombic prism may be 

 regarded as the primary form, M on M', 

 95 20'. 

 compact, 

 hydrous. 



crystallised. An oblique rhombic prisrn^ 

 P on M or M', 97 30' ; M on M', 37 30'. 

 The planes of the crystals I have mea- 

 sured are not sufficiently perfect to afford 

 very accurate measurements. 



The difference between the forms of 

 these phosphates was I believe first ob- 

 served by Mr. Levy, 

 fibrous, 

 seleneuret. 



of Silver and Copper. Eukairite. 



sulphate. A doubly oblique prism^ P on M, 127 30' ; 



PonT, 108; M on T, 123. 

 sulphuret. Glance copper. 



crystallised. The form under which the crystals 

 usually occur is that of a regular hexago- 

 nal prism^ with its terminal edges re- 

 placed. Mr. Levy found that the solid 

 angles of the prism might be removed by 

 regular cleavage, exhibiting thus an ana- 

 logy to Quartz. The primary form may 

 therefore be an acute rhomboid., P on P', 

 71 30'; as measured by W. P. 

 compact. 



From the published analyses there 

 appear to be two different sulphurets, 

 in which the proportions of copper and 

 sulphur differ. The form indicated here 

 is that of the Cornish sulphuret. 



of Copper and Bismuth. 



of Copper and Silver. 



of Copper and Iron. Copper pyrites ; yellow 



copper ore. 



