thap. 1 1.] Soap Rock, French Cbalk, &c. 6$ 



head cOnfift of magnefia united with flint j but the 

 latter ufually predominates. Moil of them are foapy 

 to the touch, and fo foft that they may be cut into 

 various utenfils*- Of thefe the following are the moft 

 remarkable: 



i. Steatite 83 lapis ollaris> or SOAP ROCK, is of various 

 colourSj but chiefly of different fhades of green. It does 

 hot become ductile in water, and is fufed with diffi- 

 culty. One variety of it is in the form of fix-fided 

 prifms, another is lamellated. 



2. Smecliis, or FRENCH CHALK, is found pretty plen- 

 tifully in Cornwall. Its colour is either white, yellow, 

 or red and white j fome fpecimens have the appearance 

 of Caftile foap* 



3. SERPENTINE STONE is of different fhades of greem 

 The ftructure of this ftone is fibrous, and it might 

 therefore be confounded with another earthy matter* 

 called afbeftos, if its fibres did not adhere fo clofely 

 together, as to efcape obfervation, when the ftone is 

 cut and polifhed. Of the ferpentine ftone there are 

 many varieties, and it is found fpotted or ftreaked with 

 a great diver fity of colours. What is commonly called 

 ferpentine ftone, is a true lapis ollaris ; but being va- 

 riegated Jike the fkins of fome ferpents, is diftin- 

 guiflied by another name. Great quantities of this 

 ftone are found in Italy and Switzerland* Where it is 

 often worked into the fhape of dimes and other vef- 

 fels. It is harder than fieatites* but not fo hard as to 

 give fire with fteel ; and lefs fmooth to the touch, 

 but is fufceptible of a good polifh j it looks like mar- 

 ble, and is often in thin pieces femitranfparent. The 

 greener forts of this ftone have been called nephri- 

 tic ; their colour -arifes from maugahefe. But the 

 term lapis nephriticus i commonly applied to jade. 



4. Micaceous earths, or TALKS, may be defined 

 VIM II* F earthy 



