BOLUS. 

 Lime . . . . 

 Loss by ignition , 



0-85 

 0-76 



100-34 



BB in the platinum forceps does not fuse, 

 but becomes pale yellow. With salt of phos- 

 phorus gives a reaction for silica and iron. 

 Partially decomposed by very dilute muri- 

 atic acid, when reduced to powder. 



Locality. Bolton, Massachusetts, U. S. 



Boltonite differs from other varieties of 

 Chrysolite in being a silicate of magnesia, 

 and not of magnesia and iron. 



Bolus, or Bole of Sinope. A variety of 

 Bole, the composition of which, according 

 to the following analysis of Klaproth, is 



nearly (Fe, Al) Si + 2H. 





Analysis : 





Silica 



. 32-0 



Alumina 



. 26-5 



Peroxide of iron . 



. 21-0 



Chloride of sodium 



. 1-5 



Water . 



. 17-0 



98-0 

 BoMBiTE, Leschenault. A mineral consi- 

 dered by Laugier to be a variety of Touch- 

 stone, of which it possesses all the characters. 

 It has no definite chemical composition or 

 form, but occurs in rounded fragments or 

 amorphous masses, derived apparently from 

 some old formation. Colour bluish-black. 

 Very finely granular. Scratches Quartz. 

 S.G. 2'2L 



Analysis by Laugier : 



50-00 



Alumina 



. 10-50 



Peroxide of iron . 



. 25-00 



Magnesia 



. 3-50 



Lime . 



. 8-50 



Carbon . . . 



. 3-00 



Sulphur 



. 0-30 



100-80 

 Locality. The environs of Bombay. 

 BoNSDORFFiTE. A hydratcd variety of 

 iolite, of a dark olive-green or greenish- 

 brown colour, found at Abo. 



Camp. Iolite + 6H. 





Analysis by Bonsdorff: 





Silica 



45-05 



Alumina . . . . 



30-05 



Peroxide of iron . 



5-30 



Magnesia . . . . 



9-00 



W^ater,with some protoxide of 





manganese and magnesia. 



10-60 



100-00 



Brit. Mus„ Case 32. 



BORACITE. 49 



BoORT, BoRT, or BowR. A kind of Dia- 

 mond, forming from two to ten per cent, of 

 the rough diamonds imported from the 

 Brazils. It is generally of a spherical shape, 

 and appears to be formed of a confused mass 

 of interlaced and twisted parts, like the knots 

 in a piece of wood. For this reason it can- 

 not be cleaved like ordinary Diamonds, and 

 is only of use as a material for polishing 

 other stones, for which purpose it is broken 

 and reduced to powder in a mortar. Al- 

 though usually round, it sometimes presents 

 crj'stalline forms, in which case the}' are 

 generally badly defined, at the same time 

 that the stone itself has a more uneven out- 

 side than ordinary rough Diamonds. Its 

 colour is mostly greyish -white, or blackish, 

 and it is less frequently found coloured than 

 the more regularly crystallized stones of the 

 same class. Its specific gravity is also 

 somewhat greater than that of ordinary 

 Diamonds. 



M. P. G. Horse-shoe Case, No. 3 (under 

 glass shade) ; No. 4. 



BoRAcio Acid, Phillips. See Sassolin. 



BoRACiTE. Cubical, tetrahedral. Occurs 

 in transparent and colourless cubes, with 

 dodecahedral and tetrahedral surfaces : also 

 amorphous. Colour white, inclinine: to 

 grey, yellow, or green. The opaque white 

 crystals are not so hard, and contain a pro- 

 portion of carbonate of lime. Lustre vi- 

 treous, more or less translucent. Streak 

 white. Fracture conchoidal, uneven. Pyro- 

 electric. Harder than Felspar. H. 4-5. S.G. 

 2 95. 



Fig. 57. 



Canp. 2(Mg3 B4) + Mg CI, or boracic 

 acid 62-50, magnesia 36-86, chloride of mag- 

 nesium 10-64 = 100. 

 Analysis by Siewert : 



Chloride of magnesium . 11.14 

 Boracic acid . . .61-34 

 Magnesia .... 26-00 

 Protoxide of iron . , . 1-52 



100-00 



BB on charcoal, fuses with difiiculty, and 

 forms a clear yellowish bead, which, on 

 cooling, solidifies to a crystalline enamel- 

 like mass, covered with needles. 



Slightly soluble in hot water, and slowly 

 dissolved by acids. 



