962 Professor Necker on Mineralogy considered 



Genus. Copper. 



Synonimes. — Native copper, Cuivre natif (Haiiy), Gediegen Kupfer (Wer- 

 ner), octaedrisher kupfer (Mohs), octahedral copper (Jameson). 



Chemical Nature. — Pure copper. 



Colour * reddish yellow. Primitive form the cube ; scratch calcareous 

 spar, scratched by fluor spar. Spec. grav. 7'8 to 8.58. When insulated and 

 rubbed acquiring positive electricity. Fusible at the 27th degree of Wedge- 

 wood's pyrometer. Soluble, with a green colour in nitric acid, and with a 

 blue colour in ammonia. 



Fu'st Species — Primitive Copper. A cube. Sign of the planes P all square ; 

 inclined to one another at 90°. — Cornwall. 



2. Octahedral Copper. — llegular octahedron. Sign of the planes r all equi- 

 lateral triangles inclined to one another at 109° 28' 16", produced by a com- 

 plete -f modification by one plane on each solid angle of the primitive form, 

 from Cornwall. 



Var. a, Transposed. — Solid, with three re-entering angles. The half of the 

 octohedron appear as if it had turned on the other half of the crystal a sixth 

 part of the circumference. Its surface consists of eight triangles and six tra- 

 peziums. 



N. B. This may be also considered as twin crystals, or a regular mode of as- 

 semblage of two individuals of this species mutually penetrating one another. 



3. Cuho-octahedral Copper. — A cube, or an octahedron, with truncated angles. 

 Sign of the planes P r. Incomplete modification by one plane on each solid 

 angle of the primitive form. Incidence of r on P 125° 15' 52". 



Yar. a. Cube being the predominating form. Incidence of P on P 90°. 

 "Var. b, Octahedron being the predominating form. Incidence of /• on r 

 109° 28' 16". 



4. Cuho-dodecahedral Copper — A cube with all its edges truncated, or re- 

 placed by one plane, or a rhomboidal dodecahedron having its six quadruple 

 angles truncated or replaced by one plane. Sign of the planes P s. Incom- 

 plete modification by one plane on all the edges of the primitive form. Inci- 

 dence of son P 153° 26' 5". 



Var. a. Cube predominating. 



Var. b, llhomboidal dodecahedron predominating. Incidence of s on s 120'. 



6. Triform Copper. — A cube truncated on all the edges and solid angles. 

 Sign of the planes P s r. In complete modification by one plane on all the 

 edges and angles of the primitive form. Incidence of P on s 153° 26' 3", of 

 « on r 144° 44' 8 ', of P on r 125° 15' 52". 



MODE OF AGGBEGATION OR GROUPS OP INDIVIDUALS OF THIS GENUS. 



These occur, as those of the preceding genera, in reticulated or diverging 

 branches, in delicate threads (Temerwar), in laminae, and grains ; also in 



• The metallic lustre and streak, the property of not bemg decomposed, and the malleability 

 being characteristic of the class, the order and the family are not repeated here. 



+ In alluding to the existing relation between the planes of the secondary and those of the pri- 

 mary form, we call complete, such modifications by which the primitive planes are entirely inter- 

 cepted, and incomplete, those which still leave remaining a part of th« primitive form. 



