some places compact and black; and in others coarse and gritty, of a
tarry colour, and when fractured shining with bright points. Hornblende
is common at Al-Madinah and throughout this part of Al-Hijaz: it crops
out of the ground edgeways, black and brittle. Greenstone, diorite, and
actinolite are found, though not so abundantly as those above
mentioned. The granites, called in Arabic Suwan,[FN#20] abound. Some
are large-grained, of a pink colour, and appear in blocks, which,
flaking off under the influence of the atmosphere, form ooidal blocks
and boulders piled in irregular heaps. Others are grey and compact
enough to take a high polish when cut. The syenite is generally coarse,
although there is occasionally found a rich red variety of that stone.
I did not see eurite or euritic porphyry except in small pieces, and
the same may be said of the petrosilex and the milky and waxy
quartz.[FN#21] In some parts, particularly between Yambu’ and Al-Madinah,
there is an abundance of tawny

[p.75] yellow gneiss markedly stratified. The transition formations are
represented by a fine calcareous sandstone of a bright ochre colour: it
is used at Meccah to adorn the exteriors of houses, bands of this stone
being here and there inserted into the courses of masonry. There is
also a small admixture of the greenish sandstone which abounds at Aden.
The secondary formation is represented by a fine limestone, in some
places almost fit for the purposes of lithography, and a coarse gypsum
often of a tufaceous nature. For the superficial accumulations of the
country, I may refer the reader to any description of the Desert
between Cairo and Suez.

[FN#1] The distance from Baghdad to Al-Madinah is 180 parasangs,
according to ’Abd al-Karim: “Voyage de l’Inde, a la Mecque;” translated by M.
Langles, Paris, 1797. This book is a disappointment, as it describes