546 



MINERALOGY. 



Qryetogno- Geographic Situation. It abounds in all the primi- 

 sv< live, transition, secondary, and alluvial districts of Scot- 



''~t~ lm *' land, England, and Ireland ; is abundantly distributed 

 throughout the continents of Europe, Asia, Africa, and 

 America. 



Uses. It is employed in the manufacture of glass 

 and artificial gems ; also in the preparation of smalt, 

 and as an ingredient in porcelain and different kinds of 

 pottery. The vesicular and corroded variety forms a 

 most excellent millstone, known in commerce under 

 the name of Bithr-stone. 



FIFTH SUBSPECIES. 



PRASE, Jameson. Prasem, Werner. 



Colour leek-green. Generally massive, and in pris- 

 matic and granular concretions. Sometimes crystalliz- 

 ed in same forms as common quartz. Surface of the 

 concretions rough and transversely streaked. Lustre 

 shining, approaching to glistening, and resino-vitre- 

 ous. Fracture conchoidal, passing into splintery. Trans- 

 lucent. 



Geognostic and Geographic Situations. It occurs in 

 primitive rocks in Scotland, Germany, and other coun- 

 tries. These beds are probably connected with primi- 

 tive trap. 



Uses It is sometimes cut and polished as an orna- 

 mental stone, but is not highly esteemed. 



SIXTH SUBSPECIES. 

 Cat's.Eye. CAT'S-EYE, Jameson. Katzenauge, Werner. 



External Characters. Principal colours grey, red, 

 and brown. Exhibits a beautiful opalescence, particu- 

 larly when cut in a convex form. Massive. Internally 

 shining, lustre vitreo-resinous. Fracture conchoidal. 

 Translucent, or translucent on the edges. 



Geognoslic and Geographic Situations. It occurs im- 

 bedded in gneiss in Ceylon. 



Uses. It is generally cut into ring-stones ; and the 

 most advantageous form for displaying its peculiar 

 lustre is the oval, with a convex surface. 

 SEVENTH SUBSPECIES. 

 Iron-Flint. IRON-FLINT, Jameson. Eisenkiesel, Werner. 



External Characters. Colours brown and red. Mas- 

 sive and crystallized like common quartz. Usually in 

 granular distinct concretions. Externally lustre shin- 

 ing, approaching to glistening ; internally glistening, 

 and vitreo-resinous. Fracture conchoidal. Opaque. 



Geognoslic Situation It occurs in veins of ironstone, 

 . and also in trap-rocks. 



Geographic Situation. In rocks near Bristol ; in 

 trap rocks that lie over white limestone, island of Rath- 

 lin, off the coast of Ireland ; and in trap-rocks near 

 D unbar in Scotland. 



EIGHTH SUBSPECIES. 

 Hornstone. HORN STONE. Jameson. Hornstein, Werner. 



There are three kinds, viz. Splintery Hornstone, 

 Conchoidal Hornstone, and Woodstone. 



Splintery First /kzW._SpLiNTERY HORNSTONE, Jameson. 

 Hornstone. Splittriger Hornstein, Werner. 



External Characters. Colours grey, red, and green. 

 Massive. Internally dull. Fracture splintery. More 

 or less translucent on the edges. 



Geognotlic Situation Occurs in veins in primitive 

 rocks. 



Geographic Situation. It occurs in primitive dis- 

 tricts in Scotland and England, and in various quarters 

 on the continents of Europe, Asia, and America. 

 Conchoi- Second Kind CoNcnomAL HORNSTONE, Jameson.-^ 

 <ial Horn- Muschlicher Hornstein, Werner. 



stone. External Character* Colours grey, white, and red. 



Massive. Internally glimmering, sometimes approach- 

 ing to glistening, and lustre vitreous, Fracture con- 



choidal. Translucent, but in a lower degree than Oryctogno. 

 splintery hornstone. sy. 



Geognostic Situation It occurs in metalliferous veins ^~~~<~~~' 

 and agate veins ; also, in imbedded portions, in pitch- 

 stone porhyry, in striped jasper, and along with clay, 

 stone porphyry. 



Geographic Situation It is found along with clay- 

 stone in the Pentland Kills near Edinburgh ; also in 

 Saxony and Bohemia. 



Third Kind WoonsTONE, Jameson. Holzstein, Wer. Woodstone. 

 ExicrnalCharaclers Colours grey, red, brown, black, 

 and yellow. Occurs in rolled pieces, and in the shape 

 of trunks, branches, and roots. External surface un- 

 even and rough. Internally dull, sometimes glimmer- 

 ing and glistening, according as it is more or less of the 

 nature of the two preceding subspecies. Cross fracture 

 imperfect conchoidal ; the longitudinal fracture splin- 

 tery and fibrous. Generally translucent on the edges ; 

 sometimes feebly translucent. 



Geognustic Situation It is imbedded in sandy loam 

 in alluvial soil ; and it is said also in a kind of sand- 

 stone-conglomerate and clay-stone. 



Geographic Situation It occurs at Loch Neagh in 

 Ireland : at Chemnitz and Hilbersdorf in Upper Saxon y, 

 and in many other places. 



NINTH SUBSPECIES. 



FLINTY-SLATE, Jameson. Flinty. 



Twpkinds,viz.CommonFlinty-Slate,andLydian Stone. Slate. 



First Kind COMMON FLINTY-SLATE, Jameson. Ge- Common 

 meiner Kieselchiefer, Werner. Plinty- 



Exlcrnal Characters Colours grey, red, and black. Slate. 

 Often traversed by quartz veins. Occurs massive. In. 

 ternally faintly glimmering, almost dull. Fracture in 

 the great slaty, and in the small splintery. More or less 

 translucent, and passes into translucent on the edges. 



Geognoslic Situation It occurs in beds and imbed, 

 ded masses in clay-slate and grey- wacke; and in round- 

 ish and angular masses in sandstone. 



Geographic Situation It occurs in different parts of 

 the great tract of clay-slate and grey-wacke, which ex- 

 tends from St. Abb's Head to Port Patrick ; also in the 

 Pentland Hills near Edinburgh. 



Second Kind. LYDIAN-STONE, Jameson. Lidischer- j ydian 

 stein, Werner. stone . 



External Characters Colour greyish-black, which 

 passes into velvet-black. Occurs massive. Traversed 

 by quartz veins. Internally glimmering. Fracture ge- 

 nerally even, and approaches sometimes to flat conchoi- 

 dal. Opaque. 



Geognoslic and Geographic Situation It occurs in 

 primitive, transition, and secondary rocks in Scotland, 

 England, and other countries. 



Use Tins mineral is sometimes used as a touch- 

 stone for ascertaining the purity of gold and silver. 

 TENTH SUBSPECIES. 



FLINT, Jameson. Feurstein, Werner. .. 



External Characters. Colours grey, yellow, brown, 

 and red. Besides massive, in plates, in angular grains 

 and pieces, it occurs also in globular and elliptical rolled 

 pieces, in the form of sand, and tuberose and perforated. 

 Sometimes occurs in lamellar concretions, which are 

 either straight or concentrically curved. Internally 

 lustre glimmering. Fracture perfect and large, and 

 rather Hat conchoidal. Translucent ; the blackish va- 

 rieties are seldom more than translucent on the edges. 



Constituent Parts. Silica 98. 



Lime . 0.50 



Alumina . 0.25 

 Oxide of iron 0.'25 



Loss . 1. 100 



Vauqueliti,Joiirn. de Mines, n, xxxiii. p. 702. 



