Dec. 1861.] 



Geology of the Neilgherries. 



241 



veins of Quartz loaded with garnets, some in an entire state, and 

 others run into a mass, manifesting that the Quartz in a liquid 

 state traversed the garnet rock, and in its passage through it, 

 caught up the garnets, vitrifying many of them. 



Detached pieces of these veins are scattered on the surface, and 

 present a cellular form, owing to the garnets having decomposed 

 and fallen out. The black garnet occurs, though rarely, in this 

 locality. Amongst other specimens I collected here are. 



A stone consisting wholly of very small dark red garnets aggre- 

 gated. 



An ochreous scaly iron ore found in fissures of the garnet 

 rock, being an aggregation of thin orange yellow scales, dull in 

 one direction and presenting a waxy lustre in the other. The 

 numerous plates intersecting and lying on each other give the 

 specimen a striated aspect. On being touched by the finger, the 

 scales adhere to it and soil strongly. Touch meagre. The mineral 

 is a peroxide of iron. It is associated with shining scales of an- 

 other iron ore. 



The garnet conglomerate has a matrix of indurated clay, in 

 color varying from lead blue to a dirty yellow. It includes 

 numerous Garnets and fragments of Quartz and Felspar. 



This conglomerate is accompanied by a Breccia, having a similar 

 base enclosing angular fragments of white and Amethystine 

 Quartz, pieces of Felspar, and red blotches, evidently the remains 

 of decomposed garnets. 



The very frequent association of garnets with iron, in con- 

 nection with the extensive diffusion of these minerals on the Neil- 

 gheries, is a subject worthy of attentive consideration. At pre- 

 sent I have before me a piece of Quartz vein broken out of a rock 

 full of iron, for the sake of a remarkably fine carbuncle (precious 

 garnet) embedded. The Quartz is entirely crystalline the result 

 of slow cooling, and is of various colors due to the contiguous iron. 

 Carbuncles of different sizes, from an inch in diameter to such as 

 are objects for the microscope, are included in the Quartz, having 

 their edges and angles so fused and run into clots, as to obliterate, 

 the crystalline form. Empty geodes in the Quartz, the concavities 

 of which are impressed with marks, and indentations, correspond- 



