70 GEOLOGY OF THE SECOND DISTRICT. 



the calcareous matter ; or whether all the materials were blended together at first, and the 

 arrangement effected by molecular attraction afterwards, are questions not easily solved. 



Serpentine, whether j)urc, or combined with limestone, forms a beautiful and ornamental 

 marble. In either variety, it is mottled, striped or spotted, and rarely homogeneous. One of 

 the finest varieties of the light clouded serpentine is in Pitcairn. A large quantity of the 

 rock has been blasted out, in pursuing a vein of galena. It is, however, far from water 

 carriage, and the heavy expense for transportation would exclude it from market. Another 

 serpentine, still more beautiful, but nearly black, with light colored veins, has been discovered 

 near Butlcrfield lake in Jefferson county. This is fully equal to the Italian marble, and even 

 with its present disadvantages, its distance from water communication, must force its way 

 into favor. There is a softness and delicacy about it which makes it superior to what is called 

 the Egyptian marble. 



The greatest difficulty in giving a fine polish to the serpentine marble, is the hardness of 

 the carbonate of lime, which does not wear so fast as the serpentine ; and hence, there re- 

 mains a dullness of surface, which does not exist where the substance is homogeneous, as in 

 the common marbles ; but by care, and the employment of fine materials for smoothing the 

 surfaces in the first place, a perfect polish may be given. 



Origin of Serpentine. 



Most writers place serpentine among the unstratified rocks, and my own observations have 

 led me to adopt the same conclusion. By some it has been compared to trap, a rock which 

 is found injected among the other masses in the form of veins or dykes. Although serpentine 

 is clearly an unstratified rock, and in this respect resembles trap, yet, so far as I have observed, 

 it never occurs in injected veins or dykes ; and admitting its igneous origin, it is an interesting 

 fact that it should not sometimes thus occur. It is often intimately blended with limestone, 

 in which it is found often separated in large and small masses ; and when it occurs distinct 

 from this rock, it is in irregular beds of a rounded form, never pursuing a range or strike like 

 a vein or trap dyke, or the layers which compose a stratified rock. It appears, therefore, in 

 great irregular masses, broken into blocks more or less angular, and checked in various ways. 

 It becomes brown, or a dirty yellowish brown by weathering, which affects the rock some- 

 times to the depth of two or three inches. If an igneous rock, it seems to have been poured 

 out in the state of thick paste, and at a lowei temperature than most igneous rocks when 

 projected to the surface. As it does not appear in veins or dykes, so it does not appear to 

 have altered the rocks adjacent to it. It therefore stands by itself in some respects, being very 

 probably an igneous rock. Though not metamorphic, still it is peculiar in the mode of its 

 occurrence ; its peculiarity consisting, as before hinted, in its massive character, in its not 

 occurring in dykes, nor affecting the adjacent strata like ignited moulten rocks. 



