Count de Bournon’s Description of 
substances that are met with in this matrix, quartz is one of the 
most rare. It is generally of a dull white colour, and has but a 
small degree of transparency. 
Mica and Talc. These two substances are not very common 
in this matrix, yet they are more so than quartz. The mica has 
a silvery hue, sometimes slightly inclining to green ; and, in the 
pieces of the matrix in which it is found, it generally appears in 
small detached spangles. 
The talc is generally of a pale green colour ; and, in those 
parts of the matrix where it is met with, it is in pieces nearer 
each other than was the case with respect to the spangles of 
mica. Sometimes it forms small masses, little or not at all mixed 
with any other substance. At other times, it is found in that 
very divided or earthy state (seldom without some heterogeneous 
mixture) which has been hitherto distinguished, after Mr. 
Werner, by the name of chlorite. 
There are also, but more rarely, met with in this matrix,, 
pieces of real steatite, of a white or a greenish colour. 
According to a letter written from Tritchinopoly, the 10th of 
November, 1792, to Sir Charles Oakley, then governor of 
Madras, and communicated by him to Mr. Greville, it ap- 
pears that the imperfect corundum of the Carnatic, as well as 
the matrix in which it is contained, forms, in the place from 
whence it is procured, distinct strata ; and that these strata are 
accompanied by a substance which is in considerable abun- 
dance, and which cannot be better distinguished than by the 
name of talcy mica. This substance is easily separated from the 
matrix of corundum-;' and it is. usual to separate it, on the spot,, 
before the pieces containing the corundum are sent away for 
the purposes of commerce. Some of it was sent to Mr, Greville- 
