S 8 4 S A B U R R Æ.

It burns to a something blacker colour.

It is common on the shores in many parts of Wales, where the Gentlemen have itgathered, and use it, as we do the Genoese, to strew over writing.

3. Saburra scintillans , tenuis , nigro cceruka .

Fine, blueijh blacks glittering Gritt.

This is a very bright and elegant Gritt; it is moderately fine, very remarkably heavy,of a fine elegant blueish-blaek colour, and great brightness; the glittering particles inthis not being like those in the two foregoing scattered among the mass of the whole,but being in this really the most numerous, and in greatest quantity of any ; the con-stituent particles of this are very various and irregular in size and figure ; it feels con-siderably harsh and rough between the fingers, and shook up in water settles imme-diately, without leaving the least muddiness in it.

Examin’d by the Microscope, it appears a congeries of various colour’d fragments ofStone and Spar, some reddish, some greenish, and some blackish, mixed among amultitude of particles of various sizes, shapes and figures, but all of a blueish black, andof very glossy surfaces j and most of them if nicely examin’d, either plated or approach-ing to a cubic shape; these make the body of the mass, and are evidently no other thanfragments of a very fine lead ore, the stony particles among these are probably brokenfragments of Stone and Spar which have lain about the ore in the earth, and the wholeis most likely to have been wash’d out of the cliffs by storms, and broken into thesesmall pieces by the motion of the water on the shores; this contains no iron ore, andconsequently no part of itL adheres to the Magnet.

It makes a slight effervescence with Aqua Fortis, which is probably owing to thesparry matter contain’d in it.

It burns like the others to a something darker colour, and being richer in lead thanthe rest, cakes together into lumps with the common degree of fire us’d on this occasion.

It is common like the former on the shores of Wales.

FOSSILS