GLEANINGS 
IN 
SCIENCE. 
25. — January , 1831. 
I. On the Minerals of the Rajmahal Cluster of Hills. By Dr. F. 
Buchanuan. 
[From his unpublished MSS.] 
This is the only part of India, where I have seen a great mass of stony 
matter disposed in what are called horizontal strata; nor is it every where 
in these hills that this position can be traced, and it is chiefly observable on their 
higher parts. There it may be in general traced, wherever any considerable excava- 
tions have been made, or wherever there are abrupt precipices. Such however are 
not common, for although the hills are steep, they are not broken by great rocks, 
and the stones, by which their surface is covered, are generally small detached 
masses. Towards the roots of the hills, again, in many places, the rocks are 
absolutely devoid of visible stratification. 
The great mass of these hills consists of what appears to me to be the variety 
of trap, called whinstone, in Tur ton’s translation of the Systema Naturae 1 (vol. 7, 
page 127), although I am not clear, that it is not a compact lava (vol. 7, page 127), 
between which stones I know of no proper limit. It is found in detached 
masses on the bank of the river at Rajmahal and Sakarigali ; but both there, 
1 Geology, as a science, is of recent growth, and even at the present day this depart- 
ment of it, the nomenclature of rocks, is little understood, and has received scarcely 
any attention from geologists. In the time of Linnaeus this was still more the case, 
and, in fact, notwithstanding his fame, as a botanist, mineralogy owes Linnaeus nothing. 
Whinstone is a provincial term, occasionally applied to greenstone, occasionally to 
basalt. Greenstone is a granitic compound of hornblende and felspar, or augite and 
felspar, according to the majority of geological writers. Basalt is composed almost 
entirely of hornblende, and the grain is generally so minute as to give it an a mos 
compact structure. Compact lava in hand specimens often bears a great 7 
basalt ; it is said by Jameson to have a less specific gravity ; but this may 
The presence of olivin, as an imbedded mineral, is said, where it exists, to orm au em 
pirical distinction of basalt. The more crystalline varieties ot this rock are ess la e 
to be mistaken. It would be very interesting to identify all the rocks here spoken o , 
which might be easily done if any gentleman, having occasion to visit that part o 
the country, would take the trouble to forward specimens to the Secretary o tie 
Physical Class Asiatic Society. Such specimens, if as large as a cake o 
soap, would be of a convenient size ; they should have a fresh fractuie on, at ' 
side, and they might be put up in country paper, with a label, stating where o itaine , 
with any other information in the collector’s power to communicate. Ed. l - 
NEW SERIES, NO. I, 
