132 ERYTHRITE. 



Erythrite, Thomson. A flesh-coloured 

 Felspar, found in amygdaloid, near Kil- 

 patrick, in Dumbartonshire. S.G. 2-541. 

 Analysis, by Thomson : 



Silica 67-90 



Alumina .... 1800 

 Peroxide of iron . . . 2-70 



Potash 7-50 



Lime 1-00 



Magnesia .... 3-25 



10035 

 Name. From h^&so?, red. 

 Erz. German for Ore. 

 EscARBoucLE, French. See Carbuncle. 



ESCHENITE. See iEsCHYNIXE. 



EscHWEGiTE, Dufrenoy. A variety of 

 Anthosiderite, occurring in brownish fila- 

 ments, associated with Specular Iron. 



EsMARKiTE, Erdmann. A hydrated lolite 

 from Brakke, near Brevig, in Norway, cor- 

 responding in composition to Iolite + 3 H. 

 S.G. 2-709. 



It occurs in large rounded prisms, with a 

 cleavage parallel to th3 terminal face. H. 

 betvveen Calc-spar and Fluor. 



BB fuses at the edges to a grey glass. 



Name. After M. Esmark. 



EsMARKiTE, Hausmann. See Datho- 



LITE. 



EssoNiTE, Ha'dy. See Cinnamon Stone. 

 Etain Oxyde, Haiiy. See Cassiterite. 

 Etaix Pyriteux, "^ 



''E™S„.™Ki [seeT,.Pva,x.s. 

 Haiiy. J 



Etain Vitreux, De Born. See Cassi- 

 terite. 



Etites. Kidney-form hydrous peroxide 

 of iron. 



Eucairite, Berzelius. Massive; in thin 

 superficial black films, staining the calcare- 

 ous spar in which it is contained. Colour 

 between silver-white and lead-grey. Lustre 

 metallic. Texture granular. Streak grey 

 and shining. Soft ; easily cut with the 

 knife. Fracture fine-grained. 



Comp. Selenide of silver and copper, or 

 C-u Se + Ag Se = ("G-u, Ag) Se = copper 

 25-3, silver 43-1, selenium 316 = 100-0. 

 Analysis, by Berzelius : 



Selenium .... 2G-00 



Copper 23-05 



Silver 38-93 



Gangue .... 8-90 

 Carbonic acid and loss . . 3-12 



100-00 



EUCLASE. 



BB gives off a strong odour of selenium : 

 on ciiarcoal fuses readily to a grey metallic 

 globule, which is not malleable. 



Soluble in boiling nitric acid ; on the 

 addition of cold water to the solution a 

 white precipitate is formed of selenite of 

 silver. 



Locality. This very rare mineral has 

 only been met with in Norway, at the 

 copper mine of Skrickerum in Smaoland. 



It was discovered and analysed by Berze- 

 lius, who named it Eukairite (from s^", well, 

 and xxi^b;, opportune) in allusion to its dis- 

 covery soon after the completion of his 

 examination of the metal selenium. 



Brit. Mus., Case 4. 



Euc;hroite, Breithaupt. Rhombic. Pri- 

 mary form a right rhombic prism. Colour 

 bright emerald-green, with a vitreous lustre, 

 and considerable double refraction. Trans- 

 parent to translucent. Streak pale apple- 

 green. Rather brittle. Fracture uneven to 

 small conchoidal H. 3 5 to 4. S.G. 3-389. 



Fig. 185. 



Comp. Cu4 As + 7H = oxide of copper 

 47-15, arsenic acid 34-15, water 18-70 = 100. 

 Analysis, by Turner : 



Oxide of copper . . . 47-85 

 Arsenic acid . . .33-02 

 Water ig-gQ 



99-67 



BB on charcoal fuses readily, giving off 

 arsenical odours and deflagrating iminedi- 

 diately; after long continued blowing, it 

 yields a globule of malleable copper, with 

 white metallic particles disposed through it. 



Easily soluble in nitric acid. 



Locality. This rare mineral is found in 

 large crystals at Libethen, in Hungary, in 

 quartzose mica-slate. It bears considerable 

 resemblance to Dioptase. 



Name. From ii'xeo'<y', beautiful colour. 



Brit. Mus., Case 56. 



EucHYsiDERiTE. See Pyroxene. 



EuCLASE. Haiiy, Phillips, Dana. Ob- 

 lique. Primary form a right oblique-angled 

 prism. Occurs in oblique four-sided prisms 

 with each of the lateral edges bevelled, and 

 variously modified and terminated. Colour- 

 less and nearly transparent, or various shades 

 of pule or bluish-green. Lustre vitreous. 



