MYSORE, CANARA, AND MALABAR, 
of gems ; but the contrary is the case here, no precious stones 
having been ever found in Mysore. It must be observed, that 
among the natives the gneiss and grey granite are called white- 
stone; and the hornblende-slate with quartz , and the quartz im- 
pregnated with iron, which I have before mentioned, are called the 
black-stone ; in fact these are found to approach to each other by 
such gradual shades, that it seems difficult to distinguish them, at 
least as genera ; ye.t in many cases the two extremes of each kind 
are so different, that they have very little resemblance to each 
other. 
In the soil of this country are found two varieties of congcar, or 
calcarious nodules. The nodules are often as large as a man’s head, 
are very irregular in shape, and frequently perforated with holes, 
apparently from having been formed round the roots of plants. 
Outwardly they have an earthy resemblance, although in some 
parts there is an appearance of irregular crystallization. They are 
very hard with a splintery fracture. Both dissolve readily, and 
with a strong effervescence, in the muriatic acid ; but deposite a 
line sand, that is insoluble. The solution contains iron, and their 
specific gravity is very considerable. The one is externally of a 
greyish white ; but its fracture has a dull purplish brown tinge, 
intermixed with shining particles, arising from its texture, which 
is a mixture of compact and sparry. Its fracture is splintery; and 
it is opake. The scratch is of a colour similar to that of the stone, 
which is hardish. Its lustre is common . The sand which it contains 
seems to be quartz , stained of a rust colour by iron, The other 
variety has, both externally and internally, a darker colour, and 
it has more numerous and larger sparry concretions. On breaking 
it, are discovered many irregular cavities lined with small, white, 
irregular crystallizations. It contains many black dots, probably 
fragments of short. 
There can be little doubt, that these nodules have been formed 
by a deposition from water, and are therefore a tophus, or calcarious 
43 
CHAPTER 
I. 
Calcarious 
nodules. 
