PHYSIOGRAPHY. 



Boltonite Boracite. 



79 



4. Boltonite occurs thickly disseminated through white limestone, 

 associated occasionally with Petalite. 



5. It is found abundantly at Bolton, (Mass.) and has also been detect- 

 ed in the neighboring quarries of Boxborough and Littleton. 



BOMBITE. 



Massive : composition impalpable. 

 - Color bluish black. 

 Hardness = 7-5. 

 1. Fusible before the blow-pipe with ebullition into a yellowish glass. 



2. Analysis. 

 By LAUGIER. 

 Silica 

 Alumina 

 Oxide of iron 

 Magnesia 

 Lime 



Carbon . . . 



Sulphur 

 3. Its geological situation is unknown. 



50-0 



10-5 



250 



3-5 



0-5 



- . 3-0 



0-3 

 It has been found only in 



Bombay. It appears to be a variety of flinty-slate. 



BORACITE. Tetrahedral Boracite. MOHS. 

 Primary form. Cube. 



Secondary forms. 



Fig. 71. 

 Fig. 70. 



Segeberg Holstein. 



LOneberg. 



Cleavage, traces parallel to the faces of the octahedron. 

 Fracture conchoidal, uneven. 



