884 PHYSIOGRAPHY. CLASS n. 



extent, converted into a tissue of crystals of the present 

 species, while the outside is covered with chloride of copper, 

 sometimes crystallized. 



5. The varieties of the present species, wherever they 

 occur in considerable quantity, are highly valuable as ores 

 of copper. 



GENUS IV. TIN-ORE. 

 1. PYRAMIDAL TIN-ORE. 



Pyramidal Tin-Ore. JAM. Syst. Vol. III. p. 155. Man. 

 p. 238. Oxide of Tin. PHILL. p. 250. Kornisch 

 Zinerz. Zinstein. WEEK. Hoffin. H. B. IV. 1. S. 53. 

 56. JZinnstein. HAUSM. I. S. 314. .Zinnerz. 

 LEONH. S. 218. Etain oxyde. HAUY. Traite, T. IV. 

 p. 137. Tabl. comp. p. 101. Traite', 2de Ed. T. IV. 

 p. 152. 

 PHILLIPS. Trans. Geol. Soc. Vol. II. p. 336. 



Fundamental form. Isosceles four-sided pyramid. 

 P == 133" 26', 67 59'. Vol. I. Fig. 8. R. G. 



a = tj 0-4547. 

 Simple forms. P oo (i) ; P (P) ; P + 1 ( 



= 121 35', 87 17 ; P + oo (/) ; [P + oo] (g) ; 



(P)* ( z ) - 159 6', 118 16, 1351T ; (P + oo) 3 



= 126 a 62' 12", 143 7' 48"; (P + ao) 5 (r) 



= 11 2 37' 12", 157 22' 48". 

 Char, of Comb. Pyramidal. 

 Combinations. 1. P + 1. P -f oo. Cornwall. 



2. P + 1. P + oo. [P + oo]. Fig. 101; 

 the prisms very short, Goshen, Massachusetts. 



S. P. P+l. P+ CD. [P+ cc]. Fig. 102. Cornwall. 



4. P. P -f 1. (P)5. [P + oo]. Cornwall. 



5. P oo. P. P + l. P + oo. [P + oo]. 

 Ehrenfriedersdorf, Saxony. 



