MINERALOGY. 



517 



Oryetogno- tals are sometimes acicular, and deeply longitudinally 

 *7- streaked. Are small, or middle-sized, and superimpo- 

 *"" ""V^ sed. Externally shining or splendent. Internally shin- 

 ing, passing into splendent, and pearly inclining to 

 adamantine. Fragments long tabular, or splintery. 

 Is translucent on the edges, or strongly translucent. 

 Colour paler blue in the streak. Sectile, and easily 

 frangible. Flexible in thin pieces. 



From the Ile of France. 



CoHitiluent Part*. -Oxide of Iron . 41.25 

 Phosphoric Acid, 19.25 

 Water . . 31.25 

 Ironshot Silica, . 1.25 

 Alumina . . 5.0098 

 Fourcroy and Laugier, in Ann. du Mus. t. iii. p. 405. 

 Geographic and Gt-ognottic Situations. It occurs in 

 Whealkind Mine, in St. Agnes's, in Cornwall ; along 

 with iron-pyrites, and magnetic-pyrites, in gneiss, in 

 the Silberberg, at Bodenmais, in Bavaria ; and in the 

 department of Allier, in France. 



SECOND SUBSPECIES. 



Fibrous FIBROUS BLUE IRON, Jameson. Fasriges Eisenblau, 



blue iron. Hautmann. Fasriges Eisenblau, Hatu. Hand. b. iii. 

 s. 1076. 



External Character*. Its colour is indigo-blue. Oc- 

 curs massive, and sometimes intimately connected with 

 hornblende, and in roundish blunt angular pieces ; also 

 in delicate fibrous concretions, which are scopifonn or 

 promiscuous. Internally glimmering and silky. ()- 

 paque. Soft. 



(jtognoilic and Geographic Situations. Europe. It 

 occurs in transition syenite at Stavern in Norway. 

 America. In West Greenland. 



THIRD SUBSPECIES. 

 EARTHY BLUB IRON, Jane ton. Blau Eisenerde, 



Earthy blue 

 iron. 



GENUS VI. GRAPHITE*. 

 Kohlen Glimmer, Mohs. 

 Cleavage rhomboidal. Streak 



Oryctogno- 

 sjr. 



GRA- 

 black. PHITE. 



One axis. 

 Hardness = 1.0 2.5. Sp. gravity = 2.7 3.0. 



This genus contains one species, viz. Rhomboidal 

 Graphite. 



1. RHOMBOIDAL GRAPHITE, Jameson. Graphit, Rhomboi- 



Werner. Erdiges Eifenblau, lie 



External Character*. In its original repository it is 

 said to be white, but afterwards becomes indigo-blue, 

 of different degrees of intensity, which sometimes passes 

 into smalt-blue. Is usually friable, sometimes loose, 

 and sometimes cohering. Occurs massive, disseminated, 

 ami thinly coating. Its particles are dull and dusty. 

 It soils slightly. Feels fine and meagre. Is rather 

 light. 



Chemical Characters. Communicates to glass of bo- 

 rax a brown colour, which at length becomes dark 

 yellow. Dissolves rapidly in acids. 



From Eckartiberff. 



Conttiluent Partt. Oxide of Iron 47.50 

 Phosphoric Acid 32.00 



Water . 20.00 99.50 



Klaproth, Beit. b. iv. s. 122. 



Geognoitic Situation. Occurs in nests and beds in 

 day- bed*, also disseminated in bog iron-ore, or incrust- 

 ing turf and peat. 



Geographic Situation. Europe. On the surface of 

 peat-mosses in several of the Shetland Islands ; and in 

 river mud at Toxteth, near Liverpool ; Iceland. AM. 

 Borders of the Lake Baikal in Siberia. America. 

 Along with bog iron-ore in alluvial soil in New Jer- 

 sey. 



UK*. Is sometimes used as a pigment. Is princi- 

 pally employed in water-colours, because, when mixed 

 with oil, the colour is said to change into black. 



Rhomboid unknown. Cleavage axifrangible. i 



This species is divided into two subspecies, viz. Scaly 

 Graphite, and Compact Graphite. 



FIRST SUBSPECIES. 

 SCALY GRAPHITE. Schuppiger Graphit, Werner. Scaly gra- 



External Characters. Colour dark steel-grey, which phl 

 approaches to light iron-black. Occurs massive, disse- 

 minated ; in coarse, small, and fine granular concretions; 

 and crystallized. Only secondary form hitherto met 

 with, is the equiangular six-sided table. Internally 

 shining, passing into splendent, and lustre metallic. 

 Fracture scaly foliated. Fragments indeterminate an- 

 gular, and blunt-edged. Streak shining, even splen- 

 dent, and lustre metallic. Perfectly sectile. Rather 

 difficultly frangible. Writes and soils. Streak black. 

 Feels very greasy. 



SECOND SUBSPECIES. 

 COMPACT GRAPHITE, Jameson. Dichter Graphite, Compact 



Werner. graphite. 



External Character*. Colour is nearly the same with 

 the preceding, only rather blacker. Occurs massive 

 and disseminated, also in columnar concretions. In- 

 ternally it is glimmering, sometimes glistening, and the 

 lustre is metallic. Fracture small and line grained un- 

 even, which passes into even, and also into large and 

 flat conchoidal ; the large is sometimes slaty longitudi- 

 nal. Fragments indeterminate angular and blunt edged, 

 and sometimes also tabular. In other characters it 

 agrees with the preceding subspecies. 



Chemical Character*. When heated in a furnace it 

 burns without flame or smoke, and during combustion 

 emits carbonic acid, and leaves a residuum of red oxide 

 of iron. 



Constituent Parts. 

 Berthollet. Graphite of Fluffier. 



Carbon . 90.9 Carbon . 23 



Iron . 9.1100.00 Iron . 2 



Alumina . 37 

 Silica . 38 100 

 Journal da Mines, N. 12, p. 16. 



Geognoitic Situation. Occurs usually in beds, some* 

 times disseminated, and in imbedded masses, in granite, 

 gneiss, mica- slate, clay-slate, foliated granular limestone, 

 coal and trap formations. 



Geographic Situation. Occurs in imbedded masses, 

 and disseminated in gneiss in Glen Strath Farrar in 

 Inverness- shire; in the coal formation near Cumnock, 

 in Ayrshire, where it is imbedded in greenstone, and 

 in columnar glance-coal. At Borrodale, in Cumber- 

 land, it occurs in a bed or beds of very varying thick- 

 ness, included in a bed of trap, which is subordinate 

 to clay-slate. This trap varies in its nature, being 

 sometimes greenstone, or trap- tuff, in other instances 



, from >;?, / vriie, "on account of iu writing quality. 



