DIAMONDS. 45
who have written on the subject without having had the advantage of visiting the spot.
Franklin
and Jacquemont give ample details of the mode of working and extraction
of the gems, their varieties, &c. The most recent contribution on
this subject is by M. Rousselet; but for the geology reference should
be made to the Memoirs by Messrs. Medlicott and Mallett of the
Geological Survey of India, as the more popular writers have given
currency to very incorrect views on this aspect of the question.
The following is an abstract of these geological accounts :—
The
diamond bed proper, a conglomerate, belongs to a group at the base of
the Lower Rewahs,* which is distinguished as the " Panna shales."
Outlying patches of these rocks occur as remnants of old spurs and
outliers from the table-land. Occurring thus, without the usual
covering of sandstone which is found on the flanks of the table-land,
earlier observers were puzzled to account for the difference, and hence
arose some of the confusion I have already described.
Mr.
Medlicott gives the following account. At the time of his visit, the
Panna miners had not got down to the diamond-bearing seam, which is not
laid bare till about March in each year :—
Panna.
The
rock diggings near Panna do not cover a surface of more than twenty
acres, they are on a low fiat rising ground at the base of the slope
from the Kymore scarp ; there were five or six pits in progress. The
section is— three feet of soil, on a smooth surface of boulder clay;
* Vide supra, p. 9,
