IS2 Professor Jameson on ihe Black Lead or Graphite 
5. — Greenstone, 
Immediately under the slate-clay is another bed of green- 
stone, varying from three to ten inches in thickness, 
6 , — Graphite and Glance-Coal, 
The bed of greenstone we have just described, rests on this 
the most remarkable bed of the whole mine. It is from three to 
six feet thick, and is composed of graphite and columnar glance- 
coal. The graphite or black-lead is either compact, scaly, or 
columnar; the glance-coal is disposed in columnar distinct 
concretions, which are arranged in rows like pillars of basalt. 
Both substances are mutually intermixed, the graphite bein^ 
frequently imbedded in the coal, and the coal included in the 
graphite. In different parts of this highly curious bed, por- 
tions of greenstone are met with. These are sometimes pure, 
or they are intermixed with the coal or graphite, or with both ; 
and these substances are so connected together, as to evince 
a simultaneous crystallization. 
7. — Greenstone, 
The bed of graphite and glance-coal rests upon a layer of 
greenstone. 
8. — Flinty-Slafe. 
The greenstone rests on a bed from ten to fourteen feet thick 
of the hard rock already mentioned, and which has been refer- 
red to flinty-slate. 
9. Sandstone, 
The lowest bed of the series, and that immediately under the 
preceding, is a sandstone, agreeing with No. 1. in consistency, 
structure, and ingredients. 
The graphite in this mine varies more in quality than that 
of Borrodale ; and, on the whole, it is to be considered as of 
inferior value. But the quantity is so considerable, and the 
average quality so good, as to authorise more extensive work- 
ings in this district, and minute and more accurate surveys of 
other parts of Ayrshire, where it is known or suspected to exist. 
III. — Black-Lead Mine of Glenstrathfaerar. 
This lately opened mine of black-lead, which is about twenty-two 
miles from Beauley, in Inverness-shire, is situated in the very ro- 
mantic and picturesque Glenstrathfarrar. The prevailing rock in 
