METAMORPHISM OF STEATITE. 553 



this association is quite common. Masses of serpentine arc also almost always found in 

 connection Avith the steatite, the two rocks passing insensibly into each other. 



It is probable that steatite and talc result, in all instances, from the alteration of other 

 minerals, of which there are many containing silicate of magnesia ; others, such as feld- 

 spar, hornblende, mica, garnet, augite, topaz, &c., contain silicates of lime, alkalies and 

 alumina, which the sulphate of magnesia might decompose and convert into silicate of 

 magnesia. Now that salt is present in some springs and rivers, Bischof calculates that 

 the Rhine at Borm contains sulphate of magnesia enough to form, "in a year a bed of 

 steatite 3460 feet long and one foot thick," and since sea water contains 110 times more 

 of this salt than the Rhine, it might make the bed 110 feet thick in the same time larger 

 than any known deposit of that substance. 



The beautiful green variety of steatite, which we regard as chlorite, undoubtedly had 

 an origin similar to talc and common steatite. This variety, however, sometimes occurs 

 in the form of veins, or dikes, of which the best examples we have met are in the west 

 part of Newfane and in Cavendish. These dikes, sometimes two or three feet thick, 

 usually penetrate serpentine. Chlorite is undoubtedly the product of alteration, and its 

 occurrence in drusy cavities and fissures, proves that it was formed in the wet way. In- 

 deed we cannot conceive how any chemical geologist can bring himself to believe that the 

 chlorite dikes in serpentine have been injected, like lava, in a molten condition. 



We wish we were able to say something satisfactorily upon the extraordinary power 

 possessed by steatite, to retain caloric when once heated. The whole mineral kingdom 

 furnishes nothing to compare with it. But no careful experiments have been made that 

 we have met with on this subject ; nor have we found any leisure to institute a series of 

 such experiments. We think that interesting results await him who shall do it. Nor 

 can we doubt that this property will be yet turned to more account than it now is, in the 

 arts and domestic economy. We think, for instance, that it can be used to advantage in 

 providing the poor of our cities with warmth in the winter, and we suspect that some 

 scientific truths yet undeveloped, respecting heat, might reward the careful experimenter. 

 But we have not room to go into details. 



Geological Position, Origin, and Metamorphism of Serpentine. 



We place this rock in the stratified class, although we have rarely met with distinct 

 stratification in it. It forms beds sometimes of great thickness in the foliated rocks, but 

 does not cut across them, as does granite, syenite and trap, though small veins of it, 

 especially of the noble serpentine, are sometimes found in limestone. In Vermont, ser- 

 pentine is almost always associated with steatite and talc, in the talcose slate formation. 

 It occurs, however, in mica schist, as at Cavendish ; and in gneiss, as at Grafton. Some- 

 times it is divided by planes, which generally are parallel to the walls, but they rarely 

 extend to any great distance, and are undoubtedly superinduced structures. Yet they 

 may be parallel to the original planes of stratification, or they may be simply joints. 



If in any other parts of the world serpentine was protruded as a melted mass into the 

 stratified rocks, we have met with no such example in Vermont. There it is most obvi- 

 ously the product of metamorphism. It probably had the same origin as steatite. Like 

 steatite it is in its purest state a hydrous silicate of magnesia, having four equivalents of 

 silica, nine of magnesia, and six of water ; or in one hundred parts, 44.02 of silica, 43.11 

 36 



