Fig. 232. 



Comp. Supposed to be a hydrous com- 

 pound of phosphoric acid and oxide of zinc, 

 ■with a small quantity of cadmium. 



Locality. The mines of Altenberg, near 

 Aix-la-Chapelle, crystallized in small drusy 

 cavities, with Smithsonite. 



Name. In honour of Dr. Hope, Regius 

 Professor of Chemistry in the University of 

 Edinburgh. 



HoRNBLEi, Karsfen, Hausmann; Horn- 

 lead. See CeomfopvDITe. 



Hornblende, Kirwan, Jameson, Phillips, 

 Werner. Oblique: primary form an oblique 

 rhombic prism. Occurs in prismatic crys- 

 tals, which are sometimes isolated, but 

 oftener confusedly aggregated, and fre- 

 quently macled ; also in imperfect crystal- 

 lizations, fibrous or columnar, the fibres 

 being sometimes like flax, sometimes lamel- 

 lar, granular, friable. Colour passing through 

 various shades ot green to blackish-green 

 on the one hand, and white on the other. 

 Lustre vitreous to pearly on cleavage faces. 

 Opaque to nearly transparent, generally 

 subtranslucent. Streak white or paler than 

 the colour. When massive tough, and dif- 

 ficultly frangible. Fracture sub- conchoidal, 

 uneven. H. 5 to 6. S.G. 2-9 to 3-4. 



^3\ 



Fig. 233. 



Under the term Hornblende are included 

 a great number of minerals, the composition 

 of which may be represented by the general 



formula (K^ 'it) 'i^'is. They are, therefore, 

 bisildcates of various protoxides and per- 

 oxides. In the formula K represents vari- 

 able proportions of lime, magnesia, protoxide 

 of iron, and protoxide of manganese. Fluo- 

 ride of calcium, also, is generally present in 

 small and variable quantities, ana there- 

 fore, most probably, in a state of mechanical 

 mixture. Many varieties of Hornblende 

 likewise contain alumina. 



Originally the name Hornblende was re- 

 stricted to the dark green and black varieties, 

 whether crystallized or massive; now, how- 

 ever, it comprehends a great many minerals, 



HORNSTOI^E. 179 



which will be found described in their pro- 

 per places. 



The principal varieties of Hornblende are 

 Actinolite, ^girine, AiTiianthu>^, Anthophyl- 

 lite, Arfvedsonite, Asbestos, Calamite,Carin- 

 thine, Cummingtonite, Diastalite, Edenite, 

 Grammatite, Mountain orKock Cork, Moun- 

 tain Leather, Pargasite,Raphilite,Tremolite. 

 Name. The name bears reference to its ex- 

 ceeding toughness. See Hornstone (name). 

 Kirwan says, "The great weight of the 

 stone called hornblende made the miners at 

 first imagine it contained some metal, but 

 finding none, except iron, they called it 

 blind, in the same sense as the vulgar do 

 nuts without a kernel. Hence the name 

 Hornblende. ^^ — Vol. i. p. 2L5. 

 Brit. Mus., Case 33. 



31. P. G. Horse-shoe Case, Nos. 1047, 

 1048—1053. 



HoRNCOBALT. A mixture of earthy Co- 

 balt and Quartz, found at Siegen, in Prussia. 

 HoRNERZ, Werner. See Kerargyrite. 

 Horn-lead. See Cromforditb. 

 Hornmangan. See Rhodonite. 

 Horn-ore, Jameson. See Kerargyrite. 

 Horn-quecksilber, Hausmann ; Horn- 

 quicksilver, Phillips. See Calomel. 



HoRN-SILBER, Hausmann, or HoRN- 

 siLVER. See Kerargyrite. 



Hornstone, Phillips. A variety of Quartz 

 resembling flint, but more brittle, and break- 

 ing with a less conchoidal fracture. It is 

 tianslucent or opaque^ and is dull, or has a 

 glimmering lu-stre. Generally grey, tinged 

 blue, green, brown, or yellow. Scarcely as hard 

 as Quartz. It is sometimes imbedded in lime- 

 stone, as in the Tyrol; in veins in Hungary 

 and Sweden, and in pseudomorphsin Saxony 

 and Bohemia. It is distinguished from Com- 

 pact Felspar, which it closely resembles in 

 appearance, by being infusible. Felspar being 

 fusible, 



Hornstone is used for snuff-boxes, seals, 

 mortars, &c., but chiefly for the handles of 

 knives and forks. It is exported from Ger- 

 many in large quantitesfor mounting butter- 

 and dessert-knives. 



"Hornstor.e difl'ers from jaspers, often by 

 its sphntery fracture, always by its trans- 

 parency, though imperfect, and want of 

 lustre; from flints b}' its fracture, dulness, 

 and hardness, but, when its fracture happens 

 to be conchoidal, by its dulness, lesser 

 transparency, and hardness; from quartz 

 by its dulness and inferior hardness ; from 

 serpentine, generally in hardness, specific 

 gravity, and fusibility; from heliotrope by 

 the aggregate of its properties."— Ai/rwan, 

 vol. i. p. 305. 



n2 



