ERUSIBITE. 



bical. The crj'stals are generally cubes, of 

 which the solid angles are replaced, and the 

 faces are mostly curvilinear. Occurs both 

 crystallized and massive. Colour of the lat- 

 ter, when recently fractured, between copper- 

 red and tombac-broAvn, but it soon acquires 

 an iridescent tarnish. Lustre metallic. 

 Streak greyish-black, and somewhat shining. 

 Slightly sectile. Easily frangible. Fracture 

 imperfect conchoidai. " H. 3. S.G. 4-4 to 5. 



Fig. 181. 



Fig. 182. 



C&mp. FeS + 2-e-uS, or (Fe,-e-u)S, (Ber- 

 zeliu&)=iron 13'8, sulphur 23"7, copper 62-5 

 = 100-0. 



Analysis of a crystallized specimen from 

 the Condurro Mine, in Cornwall, bv Plattner : 

 Sulphur . . . ."28-24 



Copper 56-76 



Iron ..... 14-84 



99-84 



BB on charcoal acquires a dark tarnish,^ 

 then becomes black, and, on cooling, red; 

 at a higher temperature, fuses easily to a 

 brittle globule, which is magnetic, and ap- 

 pears greyish- red on the fractured surface. 

 When roasted for a considerable time, and 

 then treated with a small quantity of borax, 

 affords a globule of metallic copper. 



Soluble in nitric acid. 



Localities. — English. Cornwall, crystal- 

 lized at Cam Brea, Tincroft, Cook's Kit- 

 chen, Dolcoath, HuelJewel, Huel Falmouth, 

 South Tolgus -, Somersetshire, massive at 

 Broomfield Consols. — Irish. The copper 

 mines of Kerry and Cork. — Foreign. Mas- 

 sive and compact varieties occur at Arendal 

 in Norway, Monte Catini in Tuscany, Siberia, 

 Hesse, Silesia, Hungary, and the Bannat. 



Name. From " erubesco," to turn red; given 

 by Dana in allusion to its tendency to be- 

 come tarnished, and acquire a reddish hue. 



Brit Mus., Case 7. 



M. P. G. A. 51 in Hall ; mass from near 

 Disco- Greenland. Principal Floor, Wall- 

 cases 7 (British) ; 16 and 17 (Foreign). 



Erusibite. The name proposed by Prof. 

 C. U. Shepard for a rusty, insoluble, ferric 

 sulphate, met with at the Ducktown Copper 

 Mine, in Eastern Tennessee. 



Erythrine, Beudant. Cobalt Bloom. 

 Obhque. Is found in small botr^oidal masses, 



ERYTHRTNE. 131 



and acicular diverging crj'stals, modified at 

 the edges, and whose form is a right oblique- 

 angled prism. Colour carmine and peach- 

 blossom red, sometimes whitish, or grevish- 

 white, or greenish-grey. Lustre pearlj', on 

 some faces inclining to vitreous. Varies from 

 translucent to transpr.rent. Streak the same 

 as the colour, but paler. The drv powder 

 deep lavender blue. Flexible. Sectile. H. 

 1-5 to 2-5. S.G. 2-948. 



Fig. 183. 



C^ 



Fig. 181. 



Comp. Co^ As + 8H = arsenic acid 38-43, 

 oxide of cobalt 37-55, water 24-02 = 100 00. 

 Analysis, from Joachimsthal, hy Lindaker : 

 Arsenic acid .... 36-42 

 Sulphuric acid . . . 0-86 

 Oxide of cobalt . . . 23-75 

 Oxide of nickel . . .11-26 

 Protoxide of iron . . 3-51 



Lime 0-42 



Water 23-52 



99-74 



BB on charcoal emits fumes of arsenic, 

 and melts in the inner flame to a green glo- 

 bule of arsenide of cobalt ; with fluxes yields 

 a fine blue-coloured glass. 



Soluble in muriatic or nitric acid, forming 

 a red solution. 



Localities. — English. Several Cornish 

 mines ; at Eotallack, Polgooth, Huel Unity, 

 Dolcoath, Huel Sparnon, Huel Trenwyth, 

 &c. ; Wilsworthv Mine, Devonshire ; Tyne- 

 bottom Mine, near Alston, in Cumberland. 

 — Foreign. The principal foreign localities 

 are Schneeberg, in Saxony (in micaceous 

 radiating scales). Saalfeld in Thuringia, 

 and Riegelsdorf in Hessia(in minute aggre- 

 gated crystals). Dopschau, in Hungary. 



The earthy peach blossom varieties are 

 met with in Cornwall, Alston, Dauphine, 

 and AUemont ; and a perfectly green variety 

 occurs at Flatten, in Bohemia; sometimes 

 tinges both of red and green may be ob- 

 served on the same crystal. 



Name. From htjfie,k^ red. 



Cobalt-bloom is used for the manufacture 

 of smalt. 



Brit. Mus., Case 56. 



M. P. G. Principal Floor, Wall-cases 9 

 (British) ; 20 and 40. 



k2 



