552 



MINERALOGY. 



AUochro- 

 He. 



Colophon- 

 ite 



SIXTH SUBSPECIES. 



ALLOCHROITE, Jameson. Allochroit, Werner. 



External Characters Colours, grey, brown, and 

 green. Occurs massive. Internally glimmering, rarely 

 glistening, and lustre resinous. Fracture uneven, some- 

 times even passing to conchoidal. Feebly translucent 

 on the edges. 



Geognostic and Geographic Situations. It has hither- 

 to been found only in Viuls iron-mine near Drammen 

 in Norway, where it is associated with calcareous spar, 

 reddish-brown garnet, and magnetic iron-ore. 



SEVENTH SUBSPECIES. 

 COLOPHONITE, or RESINOUS GARNET, Jameson. 



External Characters. Colours brown, red, and green. 

 Occurs massive, in angulo-granular concretions ; and 

 crystallized in rhomboidal dodecahedrons, either per- 

 fect, or truncated on the edges. Appears as if melted. 

 Internally shining ; externally splendent. Lustre resi- 

 no-adamantine. Fracture imperfect conchoidal. Trans- 

 lucent, or only translucent on the edges. 



Geognostic and Geographic Situations. It occurs in 

 beds of magnetic iron-ore, which are subordinate to 

 gneiss, at Arendal in Norway ; and in talc-slate at Sal- 

 vagnengo in Piedmont. It is also found in the Island 

 of Ceylon. 



EIGHT SUBSPECIES. 



Cinnamon CINNAMON STONE, Jameson. Kanelstein, Werner. 

 tone. Essonite, Haiiy. 



External Characters. Principal colour intermediate 

 between hyacinth-red and orange-yellow. Occurs mas- 

 sive, and in granular distinct concretions. Internally 

 shining, approaching to glistening ; and lustre resino- 

 vitreous. An indistinct cleavage sometimes visible, 

 indicating an oblique prism of 102 40'. Fracture in 

 every direction rather imperfect, and flat conchoidal. 

 Transparent and semjtransparent ; generally so impure 

 and full of cracks, that faultless specimens rarely occur. 

 Refracts single. Hardness 7, 7-5 Sp. gr. 3.5, 3.7- 



Geognostic and Geographic Stiuation. It is found in 

 alluvial deposites, and associated with quartz, tabular 

 spar, and iron- ore, in gneiss, in the island of Ceylon. 



Use. It is cut as a precious stone, and, when free 

 of flaws, is of considerable value. 



Observations Appears to be a distinct species. 



NINTH SUBSPECIES. 

 HELVINE, Jameson. Helvin, Werner. 



External Characters. Colour wax-yellow. Occurs 

 disseminated, and crystallized in tetrahedrons, which 

 are perfect or truncated on the angles. Internally glim- 

 mering or shining. Externally vitreous ; internally it 

 inclines to resinous. Fracture small-grained uneven. 

 Crystals strongly translucent. 



Geognostic and Geographic Situation. It occurs in 

 gneiss, near Schwarzenberg in Saxony. 



Observations. Probably a distinct species. 



3. PRISMATIC GARNET or GRENATITE, Jameson. 

 Prismatischer Granat, Mohs. Granatit, Werner. Stan- 

 rotide, Hauy. 



Prismatic. Prism =129 30'. Cleavage prismatoidal, 

 in the direction of the shorter diagonal of the prism. 

 Hardness = 7-0, 7.5. Sp. gr. = 3.3, 3.9- 



External Characters. Colour dark reddish-brown. 

 Occurs only crystallized, and in the form of oblique 

 four-sided prisms, sometimes truncated on the lateral 

 edges. Internally the cleavage is shining and splen- 

 dent ; fracture glistening and glimmering, with a re- 

 sino-vitreous lustre. Fracture small-grained uneven, 

 which sometimes approaches to small conchoidal. Of- 

 ten opaque, sometimes translucent, and very rarely 

 semitransparent. 



St Gotkard. 

 41. 

 S7.5 

 18.25 

 0.5 

 2.75100 



Const. Parts. Alumina, . 



Silica, . 



Oxide of Iron, . 

 Oxide of Manganese. 

 Loss, . . 



Klap. Bullet des Scien. de la Soc. 



Phil. t. i. p. 171. 



Geognoslic and Geographic Situations. Thegeogno?- 

 tic relations of this mineral are nearly the same with 

 those of precious garnet. It occurs in Aberdeenshire, 

 the Shetland Islands, county of Wicklow in Ireland, &c. 



GENUS XII. ZIRCON. 



Pyramidal. Hardness = 7.5. Sp. gr. = 4.5, 4.7. 

 PYRAMIDAL ZIRCON, Jameson. Pyraraidaler Zircon 

 Mohs. 



Pyramidal. Pyramid = 123 19'; 84 W. Cleavage 

 pyramidal, or in the direction of the lateral planes of 

 the oblique prism. 



This species is divided into two subspecies, Common 

 Zircon, and Hyacinth. 



FIRST SUBSPECIES. 

 COMMON ZIRCON, Jameson. Zirkon, Werner. 



External Characters. Colour grey, also white, green, 

 and brown ; and rarely yellow, blue, and red. Occurs 

 crystallized in rectangular four-sided prisms acuminated 

 with four or eight planes. Internally splendent, passing 

 into shining, and lustre intermediate between adaman- 

 tine and resinous. Fracture perfect and flat conchoi- 

 dal. Alternates from transparent to opaque. Refracts 

 double in a high degree. 



Chemical Character. It is infusible, without addition, 

 before the blowpipe. 



Zircon of Ceylon. 



Const. Parts. Zirconia, . 69.00 



Silica, . 26.50 



Oxide of Iron, . 0.5096.00 



Klaproth, Beit. i. s. 222. 

 SECOND SUBSPECIES. 

 HYACINTH, Jameson. Hiacinth, Werner. 



External Characters. Co\o\as red, brown, yellow, 

 grey, green, and white. Occurs crystallized, in rectan- 

 gular four-sided prisms, acuminated with four planes;set 

 on the lateral edges. Internally specular-splendent, 

 and lustre intermediate between resinous and vitreous. 

 Fracture perfect and small conchoidal. Alternates 

 from transparent to semitransparent. Refracts double. 



Geognostic and Geographic Situations of the Zircon Spe- 

 cies,inchidiiig Common Zircon andHyacinth. It occurs in 

 grains and crystals, imbedded in gneiss and sienite ; al- 

 so imbedded in basalt and lava, and dispersed through 

 alluvial soil, in Shetland Islands, Sutherlandshire, In- 

 verness-shire, Galloway, &c. The finest specimens are 

 brought from the East, principally from Ceylon. 

 GENUS XIII. GADOLINITE. 



Three axes. Prismatic. Black. Streak greenish 

 grey. Hardness = 6.5 7.0. Sp. gr. 4.0 4.3. 



This genus contains but one species, viz. Prismatic 

 Gadolinite. 



I. PRISMATIC GADOLINITE, Jameson. Prismatischer 

 Gadolonit, Mohs. Gadolinit, Karsten. 



Prism 100 nearly. 



External Characters. Colours velvet-black; very 

 rarely hyacinth-red. Occurs massive and disseminat- 

 ed ; the massive varieties sometimes composed of gran- 

 ular or prismatic concretions, the surfaces of which 

 have frequently a whitish or bluish aspect, and vary 

 from glistening to dull. It very rarely occurs crystal- 

 lized, in six-sided prisms. Internally shining ; lustre 

 resinous, inclining to vitreous. Fracture generally con- 

 choidal ; seldom uneven. 



Oryctogno- 



y- 



ZIRCON. 



Comma* 



zircon. 





Hyacinth 



GADOLI- 

 NITE. 



Prismatic 

 gadolinite 





