272 DESCRIPTIVE MINERALOGY. 



NEMALITE. 



Nemalite. NiMdtl, Phillips, Shepard and Dana. — Siliceous Hydrate of Magnesia. Thomson. 



Description. Colour white, gi-eyisli and bluish white. It occurs in the form of elastic 

 fibres, usually parallel, sometimes curved, and which are easily separable. It closely resem- 

 bles asbestus. Lustre pearly. Translucent or opaque. Hardness about 2.0. Specific 

 gravity from 2.35 to 2.44. By exposure to a red heat, it is rendered brown, gives out 

 water, becomes brittle, and is easily reducible to powder. It, however, still retains its 

 fibrous structure. Soluble in acids without effervescence. 



This mineral closely resembles asbestus, and some varieties of Dr. Thomson's stellite. 

 The action of the blowpipe, and of acids, will serve to distinguish it. Asbestus does not 

 become brown or brittle before the blowpipe, like nemalite, nor is it soluble in acids. Stellite 

 is fusible into a white enamel, and forms a jelly with muriatic acid. 



Composition. Magnesia 51.72, silica 12.57, peroxide of iron 5.87, water 29 . 67 ( TViom- 

 son). 



Geological Situation. Nemalite has heretofore been found only in thin veins in serpen- 

 tine and greenstone. It was first noticed at Hoboken in New-Jersey, by Mr. Nuttall. 



LOCALITIES. 



Rockland County. This mineral is found in very thin veins in the greenstone at Piermont, 

 where it exactly resembles the specimens found at Hoboken and Bergen hill. It is not com- 

 mon at the former locality; and the stellite, which is more abundant, may easily be mistaken 

 for it, as the fibres of that mineral are sometimes parallel. 



SERPENTINE. 



[From the resemblance which it sometimes bears to the skin of a serpent] 



Serpentine. Ckavcland, Phillips, Bcudant and Shepard. — Precious Serpentine, or Hydrous Scsquisilicate of 

 Magnesia. TTwmson. — Prismatischer Serpentine-Steatit. Mohi. 



^'S- 1^5- Description. Colour various shades of green, particularly leek-green 



and mountain-green ; also yellowish-grey and straw-yellow. It occurs 

 regularly crystallized, also massive and disseminated. The primary 

 form is said to be a right rectangular prism (Shepard). Fig. 185. The 

 form of the crystals is generally so indistinct, that a few only of the faces 

 can be traced. Texture compact, sometimes soft to the touch, tender but 

 tenacious. Fracture conchoidal or splintery. Does not adhere to the 

 tongue. Lustre resinous, inclining to pearly. Translucent, or translu- 

 cent un the edges, to opaque. Hardness of precious serpentine, 3.5; of nephrite, 7.0. 



