Reviews—The Geology of India. 327 
quartzites, schists, and gneisses, and appears to have been formed 
partly by the alteration of rocks composed of manganese-garnet ; the 
ore is typically a mixture of braunite and psilomelane, though it some- 
times consists entirely of braunite—a hard, compact, pure ore, ranging 
well over 51 per cent. of manganese. The metals chromium, cobalt, 
nickel, tungsten, titanium, and molybdenum do not call for much 
remark, and the same might apply to copper, tin, lead, etc., which 
seem to be very little worked at present. Alduminiwm might arrest our 
attention for a moment, seeing that bauxite is bound to co-exist with 
the deposits of laterite so abundant throughout the Peninsula and in 
Burma. The economic development of these deposits must, however, 
await facilities for the extraction of the purified alumina in India 
itself. 
Turning now to materials for construction, it must be admitted that 
India is famous for its building-stone. In the far south various 
igneous rocks are largely used; in the centre, slates and limestones 
from the Cuddapah Series and basalt from the Deccan trap flows 
are quarried. In Central India, etc., the great Vindhyan system 
provides incomparable sandstones and limestones, while in Bengal, etc., 
the Gondwana sandstones are used on or near the coalfields, Among 
the younger rocks the Nummulitic limestones in the north-west and in 
Assam are largely quarried, while a foraminiferal stone from Kathiawar 
is extensively used in Bombay and Karachi. Mr. Holland refers to 
the famous buildings scattered all over India in proof of the excellence 
of these materials. The Pathins and Moghuls utilized both the 
Vindhyan sandstones of Central India and the beds of marble in 
Rajputana for building their magnificent mosques, palaces, and tombs 
in the cities of Northern India. He refers especially to Fatehpur 
Sikri, where a peculiar red and mottled sandstone was used, and this 
also, if we mistake not, is equally conspicuous in the forts of Agra and 
Delhi. Moreover, there is the famous Taj, ‘‘ built mainly of white 
Makrana marble, with elaborate inlaid work of yellow marble and 
shelly limestone from Jaisalmer, onyx marble from the Salt Range, 
black calcareous shales from the Vindhyans of Chitor, malachite from 
Jaipur, carnelians and bloodstones from the Deccan trap, and red jasper 
from the Gwalior Series.”’ 
Mining for mica is also an industry of some importance; it is 
a muscovite-mica, which occurs in large pegmatite veins traversing 
mica-schists in various parts of the Peninsula. Nor should we 
altogether omit to notice the production of-sa/t, which ranks next 
to gold and coal, though a long way behind, in the Table of Values. 
Nearly half of this is obtained by evaporation from seawater, and is of 
less interest to the geologist than rock-salt, deposits of which are 
confined to the Punjab and the North-West Frontier Province—almost 
the only instance where extra-peninsular strata take precedence of the 
Peninsula in the matter of production. Some of this occurs in beds of 
Tertiary age, as at Kohat near the frontier, but the bulk is raised from 
the Mayo mines near Kheura in the Salt Range, where the beds, 
as already noticed, constitute the apparent base on which the lowest 
fossiliferous beds of India rest. The salt-deposits in this area have an 
aggregate thickness of 550 feet, ofwhich five seams of very pure 
