40 BERYL. 



Bot found crj'stallized, but in indistinct elon- 

 gated prisms or confusedly lamellar masses, 

 with a longitudinal cleavage parallel to the 

 axis of the prism. Colour dark steel-gre}', 

 inclining to pinchbeck-brown ; surface often 

 covered with iridescent spots. Lustre me- 

 tallic. H. 2 to 3. S.G. 4 to 4-3. 



Comp. FeS + Sb2 S5 = Sulphur 28-9, an- 

 timony 58*4, iron 12'7. 



Analysis of specimens from the Neue HofF- 



nung Gottes, near Freiberg, by C. v. Hauer : 



^Sulphur .... 30-53 



Iron . . . . . 10-16 



Antimony .... 59*30 



99-99 



BB fuses readily, emits vapours of anti- 

 mony, and forms a black magnetic slag. 

 Gives an iron reaction with fluxes. 



Dissolves readily in muriatic acid, giving 

 out sulphuretted hydrogen. 



Localities. Chazelles and Martourel in 

 Auvergne, associated with Quartz, Calc-spar, 

 and Lon Pyrites ; Commune of Lalaye, in the 

 Vosges; Braunsdorf in Saxony; Arany 

 Idka in Hungary; the neighbourhood of 

 Padstow in Cornwall, of a steel-grey colour, 

 and with a fibro-crystalline structure. 



Name. This mineral was first discovered 

 and described by M. Berthier, who called it 

 Haidingerite, after his friend Mr.Haidinger ; 

 but his name being already associated with 

 another species, Mr. Haidinger proposed the 

 present name in compliment to the ori- 

 ginal discoverer, 



Berthierite yields antimony of such infe- 

 rior quality, as to be worthless as an ore 

 of that metal. 



Brit. Mus., Case 11. 



BeryTj. a variety of Emerald, possessing 

 the same crystalline form, hardness and spe- 

 cific gravity, and differing from it only in 

 colour. H. 7-6 to 8. S.G. 2-67 to 2-732. 



BERYL. 



Peroxide of iron . 1-00 

 Lime . . .0-50 



2-95 



Fijr. 47. 



IX 



-^ 



Fig. 47*. 



Comp. (Be + Al) Si2 = fie + Al +4Si = 

 Glucina 14-1, alumina 19-0, silica 66-9 = 

 lUO-0. 



Analyses: a. from Siberia, hy Du Menil ; 

 h. from Hirschgasse by Bomtrager : 

 a. b. 



Silica , . . 67-00 66-90 

 Alumina . . . 16-50 18-15 

 Glucina . . . 14-50 12-20 i 



99-50 100-20 

 From these analyses it appears that the 

 colouring matter is oxide of iron. Some- 

 times the same crystal is of two or even 

 more colours, and occasionally it is irides- 

 cent. Some Beryls are quite colourless, but 

 the colours are generally blue or yellow. 

 The crystals (six-sided prisms) are of very 

 variable dimensions, from mere threads to a 

 foot or more in length, and 4 inches in thick- 

 ness ; but the latter are never sufficiently 

 perfect or transparent to be used in jewelry. 

 The finest Beryls are described by Pliny as 

 those " qui viridatem purl maris imitantur," 

 which are of a clear sea-green colour, hence, 

 crystals of clear tints of sea-green or sky- 

 blue are called Aqua-marinas, or Aquama- 

 rines. The Beryl when of good colour is best 

 cut into facets. The greenish-yellow variety 

 is sometimes mistaken for Chrysoberyl, but 

 may be distinguished from it by its inferior 

 lustre, hardness and specific gravity. Peb- 

 bles of Quartz are sometimes taken for Be- 

 ryls, and vice versa. The two may be distin- 

 guished by observing that the crystals of 

 Beryl are striated longitudinally, Mobile those 

 of Quartz are striated transversely, or at 

 right angles to the axis of the prism. More- 

 over the fracture of the two minerals is 

 widely different, for the Beryl breaks in 

 smooth planes, the faces of Avhich are at 

 right angles to the axis of the crystals, 

 whereas the fractured surface of Quartz is 

 invariably conchoidal. 



Localiiies. — English. Beryls are found in 

 Cornwall, at St. Michael's Mount, in small 

 bluish crystals in Mabe parish, 3 miles west 

 of Falmouth, and in the parish of Constan- 

 tine ; also amorphous at Huel Castle near 

 St. Just. — Scotch. Kinloch Rannoch. Mount 

 Baltoch, in diverging prisms of a pale green 

 in Granite. With Topaz, near Braemar, in 

 the alluvium of the Don and Dee. In the 

 granite and gneiss of Cairngorm, Banff- 

 shire, and in primary limestone at Port- 

 soy. — Irish. Very fine specimens, mostly of 

 a fine blue,sometimes quite transparent and of 

 considerable size, in the Mourne mountains, of 

 CO. Down. On the north-west side of the 

 small lake on Binion Hill. In fine radiating 

 crystals on Slieve Havila, and on the Chim- 

 ney Rock mountain. Also in Dublin co., in 

 the neighbourhood of Killiney and Dalkey ; 

 at the Three Rock mountain, and at Stillor- 

 gan. Near Round Wood, in Glen Malure, 

 and also in Glen Macnass, Wicklow. — Fo- 

 reign. Siberia, in the granite district of 



