1840.] 



On the Benjl Mine of Paddioor. 



173 



mica occurred loth in six-sided tables and in large irregularly-shaped 

 nests, one of which measured 2 feet in length ; the laminae highly elastic 

 and transparent. A few of the garnets were crystallized in dodecahed- 

 rons, sparingly disseminated in the rock ; one of these crystals measured 

 2 inches in diameter. The crystals of cleavlandite were remarkably 

 fine, and characteristic of this beautiful variety of felspar. The various 

 minerals composing this bed pass from the porphyritic structure into a 

 curiously fibrous arrangement : the quartz, felspar, and cleavlandite 

 occurring in alternate prismatic laminae ; sections of this rock, at right 

 angles with the long axis of the prisms, exhibit on their surfaces the 

 appearance of graphic granite. "Where this arrangement is observed, the 

 mica is partially and irregularly distributed in thin pyramidal nests, 

 rarely in direction with the laminae of the rock. The quartz and felspar, 

 •where they meet with a large nest of mica, usually lose their laminar 

 structure, becoming confused and lumpy. The felspar and cleavlandite 

 is both white and translucent, and opaque and reddish ; the latter is 

 often crossed by microscopic fissures, inclined at a great angle to the 

 axis of the prism. Ghunpore, in the Nizam's dominions, is the only 

 other locality in India where 1 have met with this fibrous rock ; it was 

 there also associated with gneiss and granite. The cleavlandite often occur 

 in large masses, with small cavities partly formed by the decomposition 

 of the rock, and partly by the intersection of the longer and more distinct 

 crystals of the cleavlandite ; it is in this gangue, and in these cavities, 

 that the Beryl, or aquamarine, is almost invariably found, in long deeply 

 striated hexahedral prisms, with small crystals of quartz. 



The wholp of the rock, composing the dyke, is divided by seams, 

 almost horizontal, intersected by fissures, thus dividing it into cuboidal 

 masses. Many of the seams are filled by a whitish earthy incrustation 

 of carbonate of lime, that has a tendency to collect in nodules. The 

 larger calcareous veins attenuate as they ascend in the rock, and appear 

 to have penetrated it from below, rather than to have been deposited 

 from above. On reaching the surface, which it often overspreads, in 

 beds of great extent, underlying the present soil, it assumes a closer 

 texture, with a nodular or pisiform surface, the interior having a sphe- 

 roidal structure, not unfrequently assimilating that of the travertine of 

 San Filippo. It has been deposited, no doubt, by springs of water 

 ascending through the subjacent strata, charged with carbonic acid, and 

 holding lime in solution. 



Small springs are still observed percolating upwards through the 

 fissures of the rock ; and, as they trickle over its surface, depositing a 

 thin black crust composed of carbon, a little iron, calcareous and saline 



