Mr. Napier on Mineral Veins and Water- Worn Stones. 238 



continue to fill every fissure or vacuity with crystals, the growth of 

 which swells open the crack, and thus causes new fractures and disloca- 

 tions, according to the variable nature of the containing rock, and the 

 amount of resistance. This gradual opening of the veins, with the 

 growth of the crystals from the sides, accounts for the isolated masses of 

 the bounding rocks found in veins, which could not possibly occur*, had 

 they been open fractures. Indeed, the hypotheses which supposes 

 minerals to be Jilled by solution from above ; or that of the injections of 

 igneous matter into an open fissure from below, are so crude and irrecon- 

 cilable with the contents, that they do not deserve our attention. The 

 facts brought forward fully justify the conclusion, that all veins, whether 

 they be mineral or not, have been formed and filled upon the same 

 principle of polar action, as described. In the east and west, or trans- 

 verse fissinres, the crystals are formed from side to side ; and in the splits, 

 longitudinally, in parallel plates," &c. 



Such, then, are, briefly, a few of the conflicting ideas upon the filling 

 up of mineral veins, exhibiting the humiliating fact, that, as yet, we know 

 nothing about it, and that many observations and experiments must yet 

 be made, before all the conditions and facts known will harmonize. We 

 cannot penetrate to the depth of a vein, to trace the orifice through 

 which the fluid mineral may have flown, or their gaseous emanations may 

 have filtered. The beautiful crystalline appearance of some of these 

 minerals, however, form no objection to the igneous theory, as some of 

 the samples of slags exhibited will show, although we have heard such 

 objections made. In examining some of the crystalline minerals, it is 

 evident, in many instances, that the crystals have been formed under the 

 influence of a current of some sort, both constant and of considerable 

 power, as the specimens on the table will show. Where and when the 

 objects upon which the crystals have formed protrude, the crystals are 

 only upon one side of the protruding object, and in one direction, such as 

 is often seen in cabinet specimens, where sulphuret of iron, carbonate of 

 iron, fluor and calcareous spar, &c., &c., have crystallized upon other 

 crystals, such as quartz, that these minerals have formed only on one 

 face of the quartz crystal ; or, if the edge of the crystal has been 

 exposed to the current, two faces are covered with the mineral, none 

 being behind. So that if the stone, or specimen, be held in a certain 

 position, the line and direction of the current may be easily traced. And 

 we find this crystallization, or deposition, has taken place with minerals, 

 and upon minerals, so that the idea of their having been in a fused or 

 vapourous state by heat is inadmissible ; at the same time, the crystalline 

 mineral must have been cither in a gaseous, or fluid state, and that for 

 a considerable time, to be thus formed, and subject to a powerful 

 influence, which produced and maintained the crystallization upon one 

 face of a crystal, or series of crystals, and not over the whole surface. 

 Whether this force be polarity in the crystals themselves, or a general 

 polarity over the mass, wo are not in a position to assert. 



