IRON. 



Subfp. I. Bro^n Iron-froth. — Colour varying between of tlie imitative forms before fpaken of. It is fometimes 

 clove-brO'.vn and fteel-grcj'. Occurs maffive, fupc-ilicial, and found in pfcudo-cr) Hals of a pyramidal fnape, «Tlli lis acute- 

 frothy. Is compofed of fcaly particles, which are gliden- angled fides. Suiface fometimes fmooth, and fometimes 

 ing, and have a metallic luftre. Fr?gments indeterminate, rough and drufy. Lullre fliining or glillening. Internally 

 blunt-edged. Intermediate between friable and folid. Soils it is from glimmering to gliftening ; intermediate between 

 ftrongly. Feels greafy to the touch. Is very foft, light, filky and rclinous. Fradlurc fibrous, paffing fometimes to 

 and fometimes even fwimming. fmall conciioidal. Fragments ufually fplintery or wedge- 

 It blackens before tlie blow-pipe without melting, and fiiapcd ; rarely indeterminate. Occurs in diltinft concrc- 

 communicates a )ellowifh-green colour to borax. tions. Streak yellowifli-brown. Opaque. Semi-hard. 

 It is g-enerally found coating compad brown iron-ftone, Brittle. Very eafily frangible, and heavy. Sp. gr. 3 789 



and brown hematite. 



One of the Shetland iflands afibrds it ; and it occurs alio 

 in Saxony, the Hartz, Norway, Carinthia, Bareulli, Car- 

 niula, and Stiria. 



Subfp. 2. Ochry-bro-jun Iron-J!one. — Co\om ye'Iowift- 

 brown, inclining to ochre yellow. Occurs maflive and dif- 

 femina'ed. Between folid and friable. Fratture earthy. 

 Internally it is dull. Fragments indeterminate, blv.nt- 

 edged. Soils coiiCderably. Is more or lefs coherent, ai.d 

 keavy. 



Imparts an olive-green colour to borax. 



It accompanies the otlier fubfpecies ; and is found in 

 Norway, Saxony, Bohemia, Bavaria, and Salzburg. 



Subfp. 3. Compid Dro'wn Iroii-Jlone. — Colour clove- 

 trown of various intcnfities, pafiing fometimes to yellowilh- 

 brown. Occurs mafiive, difTeminated, and in various imi- 

 tative forms, as Raladitic, rcniform, cellular, dendritic, &c. 

 It fometimes, aifo, appears in pfcudo-cryllals, of which the 

 cube, rhomb, and lens have been particularized. Madre- 

 pores and corallines, too, have it frequently for their bafe ; 

 as well as otiier extraneous foiTiiS. Internally it is dull, or 

 very rarely glimmering. Fratlure ufually even, fometimes 

 earthy aud fmall-grained uneven, and conciioidal. Frag- 

 ments indeterminate, edges more or lefs blunt. Streak 

 bright yollowidi-Brown, bordering on ochre-yellow. Is 

 fep.ii-hard, inclining to hard. , Rather brittle. Ealily fran- 

 gible, and heavy. Sp. gr 3.4771 to ^.^^i. 



It darkens before the blow-pipe, in confequence of the 

 lofs of oxygen, and becomes magnetic. Borax receives an 

 olive-green colour from it. 



The proportion of its ingredients, as ftated by M. 

 D'Aubuinbu, ill the 75th volnmi of the " Annafes de 

 Chiraie," is as follows : 



Peroxyd of iron - 84 



Peroxyd of niangaucfe I 



Siltx ' - - 2 



Alumine 



Volatile matter - 11 



Lofs - - 2 



The fpccific gravity of the fpecimcn from Vicdelfos was 



3-t- 



It is always accompanied with fomc of the other fub- 

 fpecies ; and frequently with quartz, calcareous and heavy 

 Ipar, and pyrites. 



Occurs in Mainland, one of the Shetland ifles ; the 

 Hartz, Saxony, Silefia, Bohemia, Suabia, the Tyrol, 

 France, 'Carinthia, &c. 



Subfp. 4. Brotvn Hemalhe. — Its colour, internally, is 

 clove-brown, which pafics to yellowifh-brown, and brownifh- 

 black. It is exhibited under a great variety of other (hades, 

 aiJ bhieifli or iron.black, pinchback-brown,bronze-ycllow,and 

 fometimes iridcfccnt. Occurs rarely inafiive ; jjfualjy in feme 

 • Vot. XIX. 



103.9,-1. 



It blackens before the blow-pipe, but docs not melt. 

 Wiih borax it enters into ebullition, and produces a dirty 

 yellow-coloured cestspound. 



Its coniHtuent parts, according to M. D'AubuifTon, 

 v.-hofe analyfjs were generally repeated two or three times, 



The fpecific gravity of the former was 3.8, and of the 

 latter 3.9. The fpecimen from Vicdeffos afforded a flight 

 trace of alumine. 



It occurs in theneweft primitive, tranfition, and fecondary 

 mountains ; but moft frequently in the two latter, where it 

 is found hning cavities in veins or beds. Its ufual attend- 

 ants are black and fparry iron-done, calcareous fpar, brown 

 and heavy-fpar, ar.d fometimes, tlioagh rarely, quartz. 



It is found in Voightiand, the Fichtelgebirge, Franconia, 

 Ileffia, and Nafiau. 



This fpecies, which is fo very abundantly diftributed in the 

 Gern'.an ilite', is of rare occurrence either in Sweden, Ruflia, 

 i\';;rv>ay, or England. In the former, it furnilhes materials 

 for very exter.iive iron-works ; and the wiought-iron pro- 

 duced from it is very valuable. 



. Sp. 8. Sp.-irry iror.-f.one. Spatheifenjliin. Le fer fl<a- 

 th'iq-ii. FerniK: ochruceum fpauformt. 



Colour yellowiiTi-grey, which pafles into yellowini-brown, 

 clove-brown, and blackiih-brown. It tarniflies on cxpofure 

 either to the air or heat, and then becomes brown or black, 

 and fometimes iridefcent. Occurs mnlTive, diffeminated, and 

 cryilallized. Its cryllals are either rhombs, lenfes, oftahe- 

 drons, or garnet-dodecahedrons. They are feldom large 

 or very fmall ; commonly middlc-fizcd and fmall. Their 

 furface is fometimes fmooth, fometimes drufy, and a little 

 rough. Internally it vt.ries from fplendent to glimmering ; 

 111 II re pearly. Fraclurc foliated. Cleavage triple. Fragments 

 rhomboidal. Occurs in granular diftind concretions. Tlje 

 light-coloured varieties are tran/lucent, efpecially on tha 

 edges: but the dark-coloured opaque. The former give a 

 greyilb-white ftreak ; the latter a yellowifh-brown. It is 

 ftnii-hard, inclining fometimes to fpft. Rather brittle. 

 Eafily frangible, and moderately heavy. Sp. gr. 3.300 to 

 3.810. 



It blackens before the bloiv-pipe, and enters into ebulli- 

 tion with borax, to which it communicates a dirty yellow 

 colour. It always effervefces more or lefs with acids.' Ac- 

 cording to Bergmans, it is compofed of 



3 1 Oxyd 



