ORDER VIII. PRISM ATOIDAL MANGANESE-ORE. 419 



not been exactly ascertained. It is supposed to contain a 

 considerable proportion of oxide of iron. It colours glass 

 of borax violet-blue, like other ores of manganese. 



3. It occurs, sometimes accompanied by prismatic Iron- 

 ore, but generally along with other ores of manganese, in 

 veins in ancient rocks, or also in porphyry. It has been 

 found in several districts of Saxony, as at Spitzleite near 

 Schneeberg,at Schimmelnear Johanngeorgenstadt,at Schle- 

 gelsberg near Ehrenfriedersdorf, &c. It occurs, besides, 

 in the Hollert mines in the district of Siegen, at Schmal- 

 kalden in Hessia, at Ilefeld and other places in the Hartz. 

 It has been found in various localities in Cornwall, Devon- 

 shire, &c. in England. 



3. PEISMATOIDAL MANGANESE-ORE. 



Prismatic Manganese-Ore (excepting the second subspe- 

 cies). JAM. Syst. Vol. III. p. 251. Prismatdidai Man- 

 ganese-Ore, or Grey Manganese*Ore. Man. p. 256. 

 Grey Oxide of Manganese. PHILL. p. 243. Grauer 

 Braunstein. WERN. Hoffm. H. B. IV. 1. S. 137. 

 Grau-Braunstein. HAUSM. I. S. 258. Grau-?Iangan- 

 erz. LEONH. S. 371. Manganese oxyde' (excepting 

 the appendix). HAUY. Traite', 2de Ed. p. 243. TabL 

 comp. p. 110. Traite', 2de Ed. T. IV. p. 261. 



Fundamental form. Scalene four-sided pyramid. 

 P = 1 30 40 7 , 120 54', 80 22'. Vol. I. Fig. 9. Ar. 



a : b : c = 1 : V 3 ' 3 7 ' V 2 '-*- 



Simple forms. P oo (o) ; P (P) ; P -f- QD (M ) 



= 994(X; (ftr l)^(y); (Pr + oo)* (,) 



= 76 36<; (P + oo)* = 142 42'; Pr (d) 



= 11419 / ; Pr+oo; Pr+l=856'; Pr -f oo. 



Char, of Comb. Prismatic. 



Combinations. 1. P oo. P + oo. Granam, 



Aberdeenshire. 

 2. Pr. P -f QD. Sim. Fig. 1. 



