Page:Travels to Discover the Source of the Nile - In the Years 1768, 1769, 1770, 1771, 1772, and 1773 volume 1.djvu/295

Rh porphyry shews itself by a fine purple sand, without any gloss or glitter on it, and is exceedingly agreeable to the eye. It is mixed with the native white sand, and fixed gravel of the plains. Green unvariegated marble, is generally seen in the same mountain with the porphyry. Where the two veins meet, the marble is for some inches brittle, but the porphyry of the same hardness as in other places.

granite is covered with sand, and looks like stone of a dirty, brown colour. But this is only the change and impression the sun and weather have made upon it; for, upon breaking it, you see it is grey granite, with black spots, with a reddish cast, or blush over it. This red seems to fade and suffer from the outward air, but, upon working or polishing the surface, this colour again appears. It is in greater quantity than the porphyry, and nearer the Red Sea. Pompey's pillar seems to have been from this quarry.

to the granite, but never, as I observed, joined with it in the same mountain, is the red marble. It is covered with sand of the same colour, and looks as if the whole mountain were spread over with brick dust. There is also a red marble with white veins, which I have often seen at Rome, but not in principal subjects, I have also seen it in Britain. The common green (called Serpentine) looks as if covered over with Brazil snuff. Joined with this green, I saw two samples of that beautiful marble they call Isabella; one of them with a yellowish cast, which we call Quaker-colour; the other with a blueish, which is commonly termed Dove-colour. These two seem to divide the respective mountains with the serpentine. In this green, likewise, it was we saw the vein of jasper; but whether it was absolute-

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