542 



MINERALOGY. 



ANDALU- 



81TE. 



Prismatic 



Andalu- 



site. 



Common 

 Andalusite, 



Oryctogno- uncommonly easily excited, even more so than in tour- 



y- M maline, or indeed in any other mineral with which we 



^"V" are acquainted. 



Chemical Cltaraclers. Fusible with ebullition into a 

 yellowish enamel. 



From Segcberg. From Lunebcrg. 

 Const. Paris. Magnesia 36'. a 16.6 



Boracic Acid 63.7100 83.4100.0 

 Pfttff. Vavquelin. 



Geognostic and Geographic Situations. This curious 

 mineral has been hitherto found only in the Kalkberg, 

 at Luneberg in Hanover, where it occurs in n particu- 

 lar bed of gypsum, along with imbedded quartz crys- 

 tals ; and in the same formation, in the Segeberg, near 

 Kiel in Holstein. 



GENUS II ANDALUSITE. 



Three axes. Cleavage prismatic, slightly oblique. 



Hardness = 7.5. Sp. gr. = 3.0 3.2. 



I. PRISMATIC ANDALUSITE, Jameson. Prismatis- 

 cher Andalusit, Mohs. 



Prismatic. Pyramid unknown. Cleavage indeter- 

 minate diagonal. 



FIRST SUBSPECIES. 



COMMON ANDALUSITE, Jameson Andalusit, Wer- 

 ner. Feldspath, Apyre, Hauy. 



External Characters. Colour flesh-red, which some, 

 times inclines to pearl-grey. Occurs massive, and cry- 

 stallized in slightly oblique four-sided prisms, in which 

 the terminal angles and lateral edges are sometimes 

 truncated. Principal fracture shining, in a low degree ; 

 cross fracture glistening, and lustre vitreous. Fracture 

 uneven. Feebly translucent. 



Chemical Characters It becomes white before the 

 blow-pipe, but does not melt. 



Constituent Parts Silica 32 



Alumina 52 

 Potash 8 



Oxide of Iron 2 94 Vauquelin, 

 Geognoslic Situation. It occurs in gneiss, mica-slate, 

 and clay-elate, 



Geographic Situation It occurs in primitive rocks 

 in Scotland and England. 



SECOND SUBSPECIES. 

 Saussurite. SAUSSURITE, Jameson. 



External Characters. Colours white, grey, and 

 green. Occurs massive, disseminated, and in rolled 

 pieces. Internally dull, or feebly glimmering. Frac- 

 ture splintery. Faintly translucent on the edges. 



Chemical Characters. -Before the blow-pipe it melts 

 on the edges and angles, but is not entirely melted. 



Geognoslic and Geographic Situations It occurs in 



Switzerland and other countries. 

 CORUN- GENUS III. CORUNDUM. 



DOM. ^ One and many axes. Cleavage rhomboidal, prisma- 



tic, octahedral. If prismatic, the specific gravity is 3.7 

 and more, and the hardness 8.5 and more. Hardness 

 = 8.0, 9.0. Specific gravity = 3.5 4.3. 



Octahedral I. OCTAHEDRAL CORUNDUM, Jameson. Octaedris- 

 Carundum. cher Corund, Mohs. 



Tessular. Cleavage octahedral. Hardness = 8. 

 Sp. gr. =r 3.5 3.8. 



This species is subdivided into three subspecies, 

 viz. Automalite, Ceylanite, and Spinel. 



FIRST SUBSPECIES. 



Automa- AUTOMALITE, Ja meson. Authomolite, Werner. 

 lite. External Charac l ers. Colour green. Crystallized, 



in octahedrons and tetrahedrons. Externally glisten- 

 ing, and lustre pearly, inclining to semi-metallic. In. 

 ternally shining on the principal fracture, but glisten- 

 ing on the cross fracture, and the lustre resinous. Frac- 

 ture flat conchoidal. Opaque, or faintly translucent on 

 the edges. 



Ceylanite. 



Spinel. 



Chemical Character. It is infusible 

 blowpipe. 



Constituent Paris. Alumina, 

 Silica, 



Oxide of zinc, 

 Iron, 

 Sulphur, 

 Undecomposed, 



Vaitquelin, Annales du Mus. t. vi. p. 33. 

 Geognostic and Geographic Situations. It occurs 

 imbedded in talc-slate, along with galena, and has 

 been hitherto found only at Fuhlun in Sweden. 

 Observation Appeal's to be a distinct species. 



SECOND SUBSPECIES. 



CEYLANITE, Jameson. Ceyknit, Werner. 



External Characters. Colours green and greyish- 

 black. Occurs crystallized in octahedrons and rhom- 

 boidal dodecahedrons. Internally splendent, and lustre 

 vitreous, inclining to semi-metallic. Fracture perfect, 

 and very flat conchoidal. Translucent on the edges. 



Geognostic and Geographic Situations. This mine- 

 ral was first found in the island of Ceylon, where it 

 occurs in the sand of rivers^ along with tourmaline, 

 zircon, sapphire, and iron-sand. It also occurs in the 

 ejected unaltered rocks at Monte Somma, and in other 

 quarters. 



THIRD SUBSPECIES. 



SPINEL, Jameson. Spinell, Werner. 



External Characters. Principal colour red ; from 

 which there is a transition on the one side into blue, 

 and almost into green ; on the other side into yellow 

 and brown, and even into white. The following are 

 its secondary crystallizations : 



I. Octahedron. 2. Tetrahedron. 3. Rhomboidal 

 dodecahedron. 4. Various twin crystals. 



Externally and internally splendent, and lustre vi- 

 treous. Fracture fl it conchoidal. Alternates from 

 translucent to transparent, and refracts single. Specific 

 gravity, 3.5, 3.8, Mohs. 



Chemical Characters. Infusible before the blow- 

 pipe without addition ; but is fusible with borax. 

 Conslit. Parts Alumina, . 82.47 



Magnesia, . 8.78 



Chromic acid, . 6.18 



Loss, . . 2.57100 



Vauquelin, J. M. No. 38, p. Si). 



Geognostic and Geographic Situation*. Europe. 



It is found in the gneiss district of Acker in Suder- 

 manland, in a white foliated granular primitive lime- 

 stone ; and in drusy cavities, along with vesuvian and 

 ceylanite, in the ejected foliated granular limestone of 

 Vesuvius. 



Asia. It occurs in the kingdom of Pegu, and at 

 Cannanor in the Mysore country. In the island of 

 Ceylon, so prolific in gems, it is found not only in the 

 sand of rivers, but also imbedded in gneiss. 



Uses It is an esteemed precious stone, but has 



neither the hardness nor fire of the red sapphire or 

 oriental ruby. 



II. RHOMBOIDAL CORUNDUM, Jameson. Ilhomboe- Rhomboi- 

 drischcr Cor'nnd, Mohs. d" 1 Corun- 



Rhomboidal. Rhomboid = 86 38'. Cleavage in the dum. 

 direction of the rhomboid, or parallel with the termi- 

 nal planes of the regular six-sided prism. Hardness 

 = 9. Specific gravity = 3.8 4.3. 



FIRST SUBSPECIES. 



SAPPHIRE, Jameson. Sapphir, Werner. Sapphire. 



External Characters. Blue and red are its principal 

 colours; it occurs also grey, white, green, and yel- 

 low. Its crystallizations are six-sided pyramids and 

 six-sided prisms. Internally, lustre splendent and 

 vitreous, sometimes inclining to adamantine. Fracture 



