146 MAGNESIA. 



and lamellar. Ti-b lamellar varieties consist of thin folia, 

 sometimes separable, but brittle; colors greenish-white, and 

 light to dark-green. 



Luster weak ; resinous, inclining to greasy. Finer varie- 

 ties translucent ; also opaque. H=2^ — 4. May be cut 

 with a knife. Gr=2*5 — 2-6. Becomes yellowish-gray on 

 exposure. Feel sometimes a little unctuous. 



Varieties and Composition. 



Precious serpentine. Purer specimens of a rich oil green 

 color, and translucent, breaking with a splintery fracture. 

 It is a beautiful stone when polished. Composition : silica 

 42*3, magnesia 44*2, protoxyd of iron 0'2, carbonic acid 0*9, 

 water 12*4. Gives off water when heated ; becomes brown- 

 ish-red before the blowpipe, but fuses only on the edges. 



Common serpentine. Opaque of dark green shades of 

 color. 



Picrolite, Schiller asbestus. A fibrous serpentine, of an 

 olive-green color, constituting seams in serpentine. The 

 fibers are coarse or fine, and brittle. Resembles some forms 

 of asbestus, but differs in its difficult fusibility. Thomson's 

 Baltimoi-ite belongs here. Amianthus is a silky variety. 



Marmolite. A foliated serpentine, of greenish white and 

 light green shades of color, and pearly luster, consisting of 

 thin folia rather easily separable. The folia are brittle, and 

 the variety is thus distinguished from talc and brucite. 

 Composition: silica 40*1, magnesia 4.1 "4, protoxyd of iron 

 2*7, water 15*7, (Shepard.) 



Kerolite. Near marmolite, but folia not separable. 



Dif. Precious and common serpentine are easily distin- 

 guished from other green minerals by their dull resinous lus- 

 ter and compact structure, in connection with their softness, 

 being easily cut with a knife, and their low specific gravity, 



Obs. Serpentine occurs as a rock, and the several varie- 

 ties mentioned either constitute the rock or occur in it. 

 Occasionally it is disseminated 'hrough granular limestone, 

 giving the latter a clouded green color : this is the verd an- 

 tique marble. 



Good Serpentine is found in the United States at Phil- 



What is the hardness of serpentine? Of what does it consist? What 

 is precious serpentine ? What are the peculiarities of marmolite and 

 kerolite 1 How ia serpentine distinguished ? How does serpenrut 

 occur? 



