CHLORITE. 



145 



also used in the manufacture of porcelain , it makes the bis- 

 cuit semi-transparent, but brittle and apt to break with slight 

 changes of heat. It forms a polishing material for serpen- 

 tine, alabaster and glass, and removes grease spots from 

 cloth. When ground up, it is employed for diminishing the 

 friction of machinery. Potstone is worked into vessels for 

 culinary purposes, at Como in Lombardy. 



CHLORITE. 



f 





^ 



Usually in dark olive-green masses, having a granular^ 

 texture ^rarely in hexagonal crystals, foliated like talc and 

 in radiated forms. Luster a little pearly. Rarely subtrans- 

 parent : subtranslucent to opaque. Laminae inelastic. H = 

 1*5. Gr = 2*65 — 2*85. Feel scarcely unctuous. 



Composition: silica 30*4, alumina 17, magnesia 34*0, 

 protoxyd of iron 4*4, water 12*6. Fuses with difficulty on 

 the thinnest eo!ges. (Yields water when heated in a glass 

 tube, -v, 



This species has lately been subdivided qh chemical 

 grounds, and the name Ripidolite applied to the new species 

 instituted. 



Dif. Its olive green color -and granular texture when 

 massive are characteristic, and the latter character will dis- 1 

 tinguish it from serpentine and potstone. From talc and its 

 varieties it is distinguished also by yielding water in a glass 

 tube ; from green iron earth in its difficult fusibility. 



Obs. Chlorite and chlorite slate, the latter an impure 

 slaty variety, form extensive deposits in many regions, 

 and the latter often contains crystals of magnetic iron, horn- 

 blende or tourmaline. 



Saponite. Soft and almost like butter, but brittle on drying ; color 

 white, or tinged with yellow, blue or red. Composition, silica 45 - 0, 

 magnesia 24*7, alumina 93, peroxyd of iron TO, potash, - 7, water 

 18-0— 98-7. From Lizard's Point, Cornwall, and the north shore of 

 Lake Superior. It may be kneaded like dough when first extracted. 



SERPENTINE. 



Rarely in right rectangular prisms. Cleavage indistinct. 

 Usually massive and compact in texture, of a dark oil green, 

 olive-green, or blackish-green coloi. Occurs also fibrous 



\ 



What effect has it in porcelain ? What is the color and usual appear- 

 ance of chlorite ? How is chlorite distinguished from green iron earth ? 

 What is the color and appearance of serpentina I 

 13 



