-e 
Corundum Slone from Asia . 411 
en cabocbon , which is often called tallow drop, from the French 
lapidaries’ term goutle de suif, convex, oval, or circular. 
A very small quantity of the Corundum powder would be 
required, as the action of the powdered Corundum and gems, 
on the lump of Corundum, would, as appears from the depth 
of the grooves, wear away from it a supply of powder, for the 
operation of polishing. It appears to be part of a larger mass, 
is of a purplish colour, and of the same laminated texture as 
the crystals of Corundum; it has this peculiarity, there ap- 
pear cracks, branching irregularly across the laminae of the 
lump, which are filled with homogeneous matter, distinguished 
however by the superior purity which might be expected to 
arise from the degree of filtration required for its deposition in 
the fissures. Some of these cracks, which terminate on the 
surface, appear to have the same crystallized arrangement which 
characterizes the laminas of Corundum. The cracks not being 
in any degree influenced in their direction by the laminae of the 
crystallized mass, it is probable they had not been consolidated, 
when they cracked ; and, from this specimen, we may expect 
to find Corundum cementing masses of stone, by the same pro- 
cess of stalactitical cementation by which quartz and calcedony 
connect great nodules and masses of siliceous stones. 
In this specimen, I consider the veins as pure Corundum, 
that is, having the same specific gravity, hardness, and tex- 
ture as Corundum crystals ; and I found the whole lump pos- 
sessed all the qualities of Corundum, except its specific gravity, 
which amounted only to 2,785; and in this property it corre- 
sponded nearly with the matrix of the Corundum crystals, or 
the vein in which Corundum is before stated to be found ; the 
specific gravity of which is 2,768. The texture of the matrix 
3 G 2 
