354 Spoctumene and its Alterations. 



In some points the oozing solution became charged from the 

 surface with a content of organic acids and their ammoniacal 

 salts — probably the "azo-humic acids" of Thenard* — combined 

 with potassa derived from the superficial weathering of the 

 granite-bed and decomposition of its Orthoclase. Here a new 

 process of alteration into Killinite ensued, by the de-oxidation of 

 the iron, the removal of the lithia and of a fourth part of the 

 silica, and their partial replacement by potassa, water, and 

 organic matter, with the great change in physical characteristics 

 described under Killinite. The larger cores of Spodumene were 

 affected chiefly at their terminations, and, in a smaller degree, 

 along the sides next the crust of Cymatolite; but smaller crys- 

 tals have been thus altered completely through. Saturation 

 with this solution has further introduced into Cymatolite its 

 dresent small content of nitrogenous organic matter. 



In all these veins there has been a subsequent separation of 

 other substances, through the decomposition of certain minerals 

 by meteoric waters. The Zircons have absorbed water, and lost 

 part of their uranium, which separated as Autunite, Torbernite 

 and, by a further decomposition, Uran-ochre, and perhaps some 

 other constituent, in the form of a pink mineral. 



The Garnets, by decomposition, have afforded much ferric 

 oxide in the form of ochre, and manganese in the form of the 

 dendritic films of Pyrolusite which abound in all the veins. The 

 Triphylite of Huntington, by absorption of water and higher 

 oxidation of certain constituents, has assumed its present altered 

 form, so that only small nuclei of the unaltered mineral may 

 sometimes be detected in the heart of a crystal. The >Spodu- 

 mene, especially at Macombers Ledge, has passed into a crumb- 

 ling mass, or even an earthy powder, possibly kaolinic, which some- 

 times becomes a white clay when moist. The Cymatolite also 

 has often become fissured and disintegrated into a clayey 

 mass. 



Compt. Keud., LXX, 1412. 



