180 • HORSE-FLESH ORE. 



Name. "This name took its rise from 

 common working miners ; they observed 

 that a sort of stone, of a dusky colour, was 

 cut through with great difficulty, by reason 

 of a tenacity which resembled thatof an horn 

 or horse's hoof* ; now, a horse's hoof, when 

 in thiu pieces, has also a slight degree of 

 transparency, this sort of stone they tliere- 

 fore called homstmie. Mineralogical writers 

 observing this combination of properties 

 not to meet together in the same stone, dis- 

 tinguished two sorts. of hornstone, both of a 

 dusky colour, one that had the semitrans- 

 parency, but not the tenacity, of a hoof or 

 horn, and another Avhich resembled that 

 substance only in colour and tenacity. This 

 distinction I tind in Henckel, on the Origin 

 of Stones.f Since that time the German 

 writers in general have confined this name, 

 with some modifications, to stones of the 

 first kind ; that is, to the stones that all 

 writers had indicated by the name ofpetro- 

 silices, and the English in particular by 

 that of chert. But the Swedes and French 

 still apply it in the latter sense.";|: — Kiru/an, 

 vol. i. p. 215. 



Horse-flesh Ore. The name by which 

 Purple Copper (Erubescite) is known to 

 Cornish miners. 



HouGiilTE, Shepard, S. W. Johnson. A 

 mineral resembling Volknerite, to which it 

 is closely related, if not identical. Colour 

 whitish externally, and bluish or reddish- 

 white within, with a faint pearly lustre. 

 H. 2-5. S.G. 2-02 to 2-03. 



Camp. A hydrate of alumina and mag- 

 nesia. 



Analysis, hy S. JK. Johnson : 



Alumina .... 23-847 

 Magnesia .... 43839 

 Carbonic acid . . . .5-833 

 Water .... 26-452 



99-995 



BB decrepitates and gives ofi" water, los- 

 ing 33^ per cent, by ignition. 



Localities. Near Oxbow, St. Lawrence co., 

 New York. Rossie, associated with Spinel. 



Name. After Dr. Franklin B. Hough, of 

 Somerville, U. S. 



This mineral is the material of pseudo- 

 morphous Spinel, and probably at times of 

 Scapolite, according to S. W. Johnson. It 

 occurs in crystals, which vary from pure 

 Spinel to octahedrons, with roanded edges, 

 and pitted or irregular surfaces. The last 



* Vogel, Mineral, p. 130. 

 f P. 400 of the French translation. 

 t VVallerius. 



HUMBOLDTILITE. 



are sometimes soft and altered, while the 

 edges or angles have the hardness of Spinel. 

 It also occurs in flattened kidney-form con- 

 cretions, with botryoidal surfaces. 



HouiLLE. French for Coal. 



HouiLLE Papyracee, Lucas. See Dy- 



SODILE. 



HooiLLE PiciFORME, Brochant. See Jet. 

 Howardite. An earthy mineral, abun- 

 dant in meteoric stones. 



Comp. Tersilicate of protoxide of iron 



and magnesia, or Fe Si^ + Mg Si'^. 



Named after Howard, meteorologist. 



HuDSONiTE, Beck. A black Pyroxene, 

 identical with Polylite, and with a similar 

 cleavage to Hedenbergite, from which it 

 otherwise differs in having a considerable 

 quantity of the silica replaced by alumina. 

 It also contains manganese sometimes. It 

 atFords a green streak, and has often a browR 

 tarnish. S.G. 3-43 to 3-5. 



Comp. (Ca, Fe)5 (Si, Al)2. 



Analysis (mean), by Smith §• Brush : 

 Silica .... 39-94 



Alumina .... 10-41 

 Magnesia .... 3-00 



Lime 10-36 



Protoxide of iron . . 30-48 



Protoxide of manganese . 0-60 



Potash 2-48 



Soda . . . . . 1-G6 

 Loss by ignition * . .1-95 



97-92 



BB fuses readily to a shining black glass. 



Locality. Orange co., New York, U.S. ; 

 near the Hudson River ; whence the name. 



HuiLE Minerals CoMMUiifE, Brochant. 

 See Petroleum. 



HuMBOLDTiLiTE §, 3Ionticelli §■ Covelli; 

 Phillips, Beudnnt. Humboldtilith Meli- 

 LiTH, Mohs. A Mellilite found on Vesuvius 

 in lava. It occurs in crystals derived from 

 a rectangular prism with a square base ; 

 cleavage parallel to the base. Colour grey- 

 ish-yellow or grey, with a vitreous lustre 

 passing into resinous. Transparent to feebly 



Fig. 234. 



translucent. Fracture uneven and splintered, 

 H. 5. S.G. 2-91 to 3-1. 



§ Named after the Baron von Humboldt. 



