ISOMETRIC COBALT PYRITES. 



Bohemia, Saxony, Calabria, and near Puy- 

 de-Dome, in France. 



This mineral was first found disseminated 

 in granite-sand, in the Risengebirge of 

 Silesia, near the source of the stream called 

 the Iser, whence the name Iserine. 



Brit. Mus., Case 37. 



Isometric Cobalt Pybites, 3Iohs. See 



LlNN^ITE. 



IsoPHANE, Berthier. See Franklinite. 



IsOPYRE, Turner, Phillips; IsOPYRIC 

 Quartz, Haidinger. Occurs in compact 

 amorphous masses, of a greyish or velvet- 

 black colour, and occasionally spotted red 

 like Heliotrope. Lustre vitreous. Opaque, 

 or faintly translucent at the thinnest edges. 

 Streak pale greenish-grey. Brittle. Frac- 

 ture flat-conchoidal. Slightly magnetic, H. 

 6 to 6-5. S.G. 2-9to8. 



Comp. Ca Si-f-(^l,Fe) "tSi = silica 49-66, 

 alumina 13'78, peroxide of iron 21-51, lime 

 lo'05 = l00. 

 Analysis, from Cornwall, by Turner : 



Silica 47-09 



' Alumina .... 13-91 

 Peroxide of iron v . . 20 '07 



Lime 15-43 



Oxide of copper . . .1-94 



98-44 



BB fuses readily to a magnetic globule. 

 On platinum colours the flame green. De- 

 composed by the acids imperfectly and Avith 

 difficvilty, but easily and completely decom- 

 posed by alkaline carbonates. 



Localities. Near St. Just and Penzance, 

 in Cornwall, forming compact masses, some- 

 times two inches thick, in granite. It is 

 associated with Tourmaline and Tin Stone. 



Name. From 'Vs?, equal, and '^'^^.fire, the 

 effect produced on it BB being similar to that 

 produced on several other minerals. 



Isopyre bears a strong resemblance to 

 Obsidian, but may be distinguished from it 

 by a fainter and less vitreous lustre. 



IspADRAN. A name that has been given 

 to Copper Pyrites, from the district of the 

 Keradagh, in'^Persia, between Tabriz and the 

 Caspian. 



Italian Chry'solite. The name by which 

 the Italian Idocrase, which is cut at Naples, 

 is commonly called. 



Ittnekite, Gmelin, Leonhard. Cubical: 

 primary form a rhombic dodecahedron. Oc- 

 curs granularly massive, with an indistinct 

 dodecahedral cleavage. Colour dark bluish- 

 or ash-grey. Lustre resinous. Translucent. 

 Fracture imperfect-conchoidal. H. 5'5. S.G. 

 2-3. 



IXOLYT. 



193 



Comp. (Na, Ca)^ Si + 3A1 Si + 6H, with 



some Na CI and Ca S. 





Analysis, by Gmelin : 





Silica .... 



34-02 



Sulphuric acid 



2-86 



Alumina 



28-40 



Peroxide of iron . 



0-62 



Lime .... 



. 7-27 



Soda .... 



. 12-15 



Potash .... 



. 1-56 



Muriatic acid 



. 0-75 



Water and sulphuretted hy 





drogeu 



. 10-76 



98-36 



BB when gentl}' heated it becomes 

 covered with blue spots like stars. Alone, 

 on charcoal, swells up strongly, and fuses 

 readily, with evolution of sulphurous acid, 

 to a blistered enamel. With borax and mi- 

 crocosmic salt, it yields a transparent glass, 

 in the latter case containing a skeleton of 

 silica. 



Dissolves quickly in muriatic acid, with 

 evolution of sulphuretted hydrogen, and for- 

 mation of a siliceous jelly. (C. Gmelin.) 



Localities. The Kaiserstuhl, near Frei- 

 burg, in dolerites; also at Sasbach and 

 Ihringen. 



Name. After the discover. Von Ittner. 



IwAARlTE, Nordenskiold. A mineral hav- 

 ing apparently the characters of Schorlo- 

 mite. It occurs either in cubical crystals 

 or massive, and contains much titanium. 

 Colour lustrous iron - black, like black or 

 crystallized Melanite, with a grey streak. 



Comp. Ca5 "fcii + -Fe Si + JT 1*2. 



BB fuses to a black glass. 



Locality. Iwaara, in the Kunsamo Kirch- 

 spiel, in Finland. 



IxiOLiTE. The name given by Nordens- 

 kiold to the variety of Tantalite found only 

 near Skogbole, in the diocese of Kimito 

 in Finland. It usually occurs in rectangu- 

 lar prisms of a blackish-grey to steel-grey 

 colour, with a weak metallic lustre. Streak 

 brown. H. 6 to 6-5. S.G. 7 to 7-25. 



It was formed into a separate species in 

 consequence of the large quantity of tin and 

 manganese it contains. 



IxoLYT, Haidinger. IxOLYTE, Dana. A 

 bituminous mineral closely resembling Har- 

 tite, but differing in the temperature at 

 which it fuses, as well as in other respects. 

 Amorphous. Colour hyacinth-reck Lustre 

 greasy. Subtranslucent in thin fragments. 

 Crumbles to powder between the fingers, 

 becomes ochre yellow and yellowish-browa. 

 o 



