384 TOPFSTEIX. 



defined dodecahedrons of a honey-yellow, 



(sometimes of an olive-green) colour, at 



Mussa, in Piedmont. 

 Analysis, bj' Bonvoisin : 



Silica 37 



Lime 29 



Iron 25 



Ghicina . . . . .4 



Alumina 2 



Manganese .... 2 



99 

 The name (from Topaz, and x/fe?, stone') 



is in allusion to the resemblance of its 



colour to that of yellow Topaz. 



ToPFSTEiN, Werner. See Potstone. 



TORBANE-HiLL COAL ; ToRBANE MINE- 

 RAL, or ToRBANiTE, Greg ^ Lettsom. A 

 kind of Brown Cannel Coal. Amorphous. 

 Compact. Colour clove-brown, without lus- 

 tre, becoming darker (deep brown or brown- 

 ish-black) on exposure to air and moisture. 

 Streak light brown or yellow. Brittle but 

 very tough. Fracture subconchoidal Comes 

 out of the mine in cubical masses like ordi- 

 nary coal. Takes fire easily, splits, and 

 burns Avith an empyreumatic odour, giving 

 out much smoke, and leaving a considerable 

 quantitv (about 20 per cent.) of white ash. 

 H, 2-5. aG. 1-2. 



Analysis, by O. 3Iather : 



Carbon.' . . . . 6081 

 Hydrogen . . . .9 18 

 Nitrogen . . . . 0'78 

 Oxygen .... 4*39 



Silica 13-19 



Alumina .... 9-50 

 Peroxide of iron . . .1-22 



Water 0-39 



Sulphur .... 0-32 

 Lime 0-27 



100-05 

 Localities. Torbane, Inchcross, Boghead, 

 Capper's and Bathvale, near Bathgate, in 

 Linlithgowshire ; in the upper Coal Mea- 

 sures of Scotland, immediately above the 

 Millstone Grit. The Torbanite occurs in a 

 bed varying in thickness from 16 inches to 

 2 feet, in contact with shales and Clay Iron- 

 stone, and resting on a bed of underclay, 

 after the manner of ordinary Coal. It occa- 

 sionally contains casts and impressions of 

 the stems of large sigillaria and other 

 fossil plants, which are also found in the 

 accompanying shales. The mass is also 

 traversed "by the roots of Sigillaria (Stig- 

 maria), wliich penetrate the bed of " under- 

 clay " on Avhich the coal is based. 



TOURMALINE. 



The Torbane-Hill Coal sometimes passes 

 into Black- band Ironstone and into ordinary 

 Cannel Coal. 



This remarkable mineral is the most 

 valuable Coal hitherto discovered for mak- 

 ing gas and oil (parafline). Dr. Andrew 

 F3'fe, from a ton of the Coal, obtained 

 760 lbs. of coke, and 14,880 cubic feet of 

 gas, the illuminating power of which was 

 equal to the light of 7-72 spermaceti can- 

 dles. It also yields, on distillation, 125 gal- 

 lons of crude oil per ton. — (See lire's Diet, 

 of Arts, (^c.) 

 31. P. G. Horse -shoe Case, No. 78. 

 ToKBERiTE, Brooke §* 3Iiller. Copper- 

 Uranite. See Chalcolite. 



ToRRELiTE, Thomson. See Columbite. 

 Named after Dr. John Torrey. 

 Touchstone. See Lydian Stone. 

 TouR3iALiNE, Werner. Hexagonal. Oc- 

 curs in crystals, which are usually termi- 

 nated differently at the opposite extremities, 

 and the prisms often assume triangular 

 forms, owing to the absence of alternate 

 faces. Sometimes occurs massive, compact ; 

 also columnar, coarse or fine, parallel or 

 divergent ; also in detached crystals. Co- 

 lour black, brown, blue, green, red, and 

 rarely white or colourless. Exhibits di- 

 chroism. Some specimens are red inter- 

 nally arid green externally ; others are red 

 at one end, and green, blue, or black at the 

 other. Of every variety of transparency, 

 from perfect clearness to opacity. Differs 

 in transparency across the prism, and in the 

 line of its axis. Streak uncoloured. Brittle. 

 Fracture subconchoidal, uneven. H. rather 

 greater than Quartz, 7 to 7-5. S.G. 2-94 

 to 3-3. 

 Pyroelectric. 



BB swells up and fuses to a slag. 



Fig. 439. 



Fig. 440. 



Fig. 441. 



Comp. (R3 ^ B) Si. 



Rammelsberg has divided Tourmaline in- 

 to five sub-groups, viz. I. Magnesia Totir- 

 maline. II. Iron-magnesia Tourmaline. HI. 

 Iron Tourmaline, black. IV. Iron-man- 

 ganese-lithia Tourmaline. V,. Lithia Tour- 

 maline. 



