Spodumene and its Alterations. 330 



scale, of the phenomena of a crystallization attended by absorp- 

 tion of water and alkalies, and by great consequent expansion 

 within a confined space. The volume of that part of the granite- 

 vein at Chesterfield Hollow which has been excavated, comprises 

 perhaps two or three hundred cubic yards of rock, and its original 

 content of Spodumene must have amounted to several tons, a 

 quantity sufficient, during alteration and expansion, to have pro- 

 duced an enormous pressure. On the one side, this mechanical 

 force of expansion has hastened the process of alteration, both by 

 the rupture of the superficies of the Spodumene, and by the pro- 

 duction of the minute sieve-like space, which has apparently sup- 

 plied the principal channel for the solutions which effected the 

 pseudomorphous change. Outwardly, great pressure was at first 

 exerted against the quartz-matrix, producing, as with the expan- 

 sion of type-metal in a mould, a sharp impression upon the 

 Cymatolite-crust— especially in the smaller prisms — of the finest 

 lines of the cast of the Spodumene, and often, around the larger 

 crystals, also crushing and rupturing the quartz, leaving it 

 seamed by the present innumerable little rifts. This was proba- 

 bly followed by a subsequent contraction of the two materials, 

 by loss of temperature and moisture, to which may be due the 

 present slight adherence between the crystals and their gangue. 

 Also, within the pseudomorphous crust, the same pressure 

 brought about a bending of fibres and dislocation of scales, 

 which resulted in the wavy structure to which Cymatolite owes 

 its name, and which, being more than a mere accident, but in 

 most localities essentially connected with the genesis of the 

 mineral, imparts to that name a peculiar appropriateness. 



The irregular transmission of pressure through the partially 

 crushed and ruptured quartz-matrix, appears to have resulted in 

 the bending, flattening, aud common distortion of the crystals. 



Again, in those crystals in which the more rapid process of 

 alteration from a termination has progressed so far along the 

 axes as to have produced blade-like cores, retaining the ortho- 

 diagonal cleavage of the parent Spodumene, the terminations 

 are found to be flat or pointed, not merely in most cases by 

 being pinched together by a pressure from without, but in many 

 instances, perhaps, by the expansion and forcible protrusion of 

 the bladed cores. 



